Unit 12: Magnetism. Background Reading

Size: px
Start display at page:

Download "Unit 12: Magnetism. Background Reading"

Transcription

1 Unit 12: Magnetism Background Reading What causes magnetism? Have you ever wondered why certain materials can be easily magnetized while others seem to be unaffected by magnets? The properties of certain metals lend themselves towards taking on magnetic properties. The individual atoms in certain metals can each produce a region called a magnetic field. Even a small sample of a metal has many atoms, and the magnetic fields of each atom generally point in different directions. The magnetic fields generally cancel out, and as a result, the sample of the metal does not demonstrate any magnetic properties. Sometime an outside influence can cause a group of atoms in the metal sample to orient in the same direction. When the atoms are producing magnetic fields in the same direction, it is called a magnetic domain. Generally, the magnetic domains throughout a material are still oriented in many different directions, and no magnetic effect would be measurable. However, when certain metal are placed in a magnetic field produced by an outside source, the magnetic domains will align, and the metal becomes magnetized. The majority of materials have very limited magnetic properties, and quickly revert back to the original state with domains pointing in random directions, but a few are able to retain their magnetism for longer periods of time. Iron, nickel, and cobalt (and their alloys) are able to form strong permanent magnets. Of these, iron is considered a soft magnet, in that it is easy to magnetize it, but it loses magnetism easily. Cobalt and nickel are hard magnets, as they are more difficult to magnetize, but once magnetized, stay magnetized well. Heating up any magnet will effectively reset its magnetic qualities, since the particles in the material vibrate more as they gain energy, and will randomize the direction of the magnetic domains. The ends of a magnetic object are known as magnetic poles. Each magnetized object will have a north and south pole. Similar to electric charges, opposite poles attract to each other and two of the same poles will repel each other. Also similar to electric charges, an object can become magnetized by bringing it close to another magnetized object. A significant difference between electricity and magnetism is that a single magnetic pole can never exist by itself, but must always be accompanied by an opposite pole. In contrast, you could have a positively charged particle without a negative one. If you break a bar magnet in half, you will end up with two smaller magnets, each with a North and South pole, rather than one piece with a north pole, and another that is a south pole. If you are interested in reading more about how a permanent magnet can form, please see the section entitled A Deeper Look At Magnetism at the end of this reading. Magnetic Fields The region in which a magnetic force can be detected is known as a magnetic field. A magnetic field is a vector quantity (has a direction) represented by the variable B. The direction of a magnetic field is defined by the direction that the magnetic pole of a compass will point in that magnetic field. Since

2 opposite poles attract, the north pole of the compass will actually point towards the south pole of a magnet. A magnetic field is graphically represented by a series of lines that point away from the north pole of a magnet and towards the south pole. The direction of the field is indicated by arrows drawn on each line pointing away from the north pole, as in the illustration to the right. Notice that the compasses are aligned so that the north end of the compass needle (the arrow head) is pointing towards the south pole of the bar magnet. Notice that the density of the magnetic field lines represents the strength of the magnetic field; areas with a stronger magnetic field will have field lines that are closer together, similar to electric field lines. If the bar magnet in the picture above were to be stood on end, so that the south pole sat on the table and the north pole was pointing up, the magnetic field would actually be going vertically perpendicular to the paper. The convention used to represent a magnetic field that goes into the plane of the paper is an (+), similar to how you would see the tail feathers of an arrow that is shot into the paper. A magnetic field coming out of the plane of the paper is represented with a dot (o), similar to the point of an arrow head fired out of the paper. You can see a sample diagram of a magnetic field coming out of the page to the right (ignore the electron for now). Earth s Magnetic Field Earth s magnetic field can be detected using a compass. Remember that the north pole of the compass points towards the south pole of a magnet. It follows that when a compass is used for navigation, it is actually pointing towards the magnetic south pole of planet Earth. Although the top of the globe is considered to be geographic north, it is actually the magnetic south pole of our planet! The cause of Earth s magnetic field is currently unknown, but many theories exist. It is unlikely that the solid iron core is a permanent magnet that maintains the magnetic field, since it is so hot that the orientation of electrons should be randomized. It has been suggested that around Earth s solid core is a region of

3 molten iron. Currents flowing through this molten metal could be responsible for producing the magnetic field around Earth. Others have observed that there may be a connection between the rate that a planet is spinning and the strength of the magnetic field produced by that planet. Venus has a much slower rotation and also has a weaker magnetic field than Earth. As you can see in the diagram to the right, the magnetic field around Earth is three dimensional, and all field lines leave the magnetic north pole (geographic south pole) and return to the magnetic south pole (geographic north). The magnetic field around Earth serves a multitude of purposes for those living on this planet. Humans are not alone in using the magnetic field of earth for navigation. Some birds have demonstrated an ability to migrate tremendous distances using their ability to sense the magnetic field. Some types of bacteria have been observed to respond to a magnetic field. All life benefits from the protection against the constant bombardment of high energy particles from our Sun and other sources. The strength of a magnetic field is measured using the unit Tesla, represented by a T. Near the surface of Earth, the strength of the magnetic field is about 0.5 T. Ordinary magnets are a bit stronger with a magnetic field of about 2.5 T. The strongest magnets would produce magnetic fields of up to 30 T. Magnetic Force Just as a charge in an electric field will experience a force, a charge moving through a magnetic field will experience a magnetic force. Although both fields can produce a force, the there are some significant difference between the two. An electric force is in the same direction as an electric field line. The magnetic force exerted on a charged particle will be perpendicular to a magnetic field. An electric charge will experience a force in an electric field even if it is at rest. An electric charge must be moving through a magnetic field to experience a magnetic force. The equation used to represent the strength of a magnetic force is: F = qvbsinθ In the equation above, F represents the magnetic force (in Newtons), q represents the charge of the particle moving through the field, v is the velocity of the charge, B is the strength of the magnetic field = magnetic field (measured in Tesla, T), and theta is the angle is between v and B. Since the sin function is used to relate the angle between the velocity of the particle and the magnetic field, we can observe that the maximum value for the magnetic force will be possible when Ɵ is 90, and the force will be zero when Ɵ is 0 (the particle moves parallel to the magnetic field).

4 We have already stated that the magnetic force will be exerted in a direction perpendicular to the magnetic field, and we now know that for a magnetic force to act on the particle, the velocity of the particle also has to be perpendicular to the magnetic field. These three values are all perpendicular to one another, meaning that they are acting in three different dimensions (x,y,z). A common convention used to determine the direction of a magnetic force is known as the Right Hand Rule. To use the right hand rule, point the fingers of your right hand in the direction of the velocity (v) of the moving charged particle. Curl your fingers towards the direction of the magnetic field (B). After doing this, your thumb will point towards the direction of the magnetic force (F). Try using the Right Hand Rule with the diagram to the right. Remember that the (+) symbol means the magnetic field is going into the desk. Point your right hand towards the right (direction of velocity), curl your fingers into the field (down towards your desk), and your thumb points in the direction of the magnetic force (towards the top of your desk). Practice Problem 1: A proton (q = 1.6 x C) moves with a velocity of 20,000 m/s up your desk (away from you) through a magnetic field of 0.7 T that points to the right of your desk. What is the magnitude and direction of the magnetic force? For the answer, check the last page of this reading. Magnetic Force on a Current Carrying Wire When a single charge moves through a magnetic field, it experiences a magnetic force. It follows that when multiple charges move through a magnetic field, they will all experience a magnetic force. If the charges are moving as a current through a wire, then the wire carrying the current will experience a net force when placed in a magnetic field. To calculate the magnetic force acting on a current carrying wire in a magnetic field, the equation for the force on a charged particle in a magnetic field can be modified to account for all of the charges moving in a wire. By multiplying the flow rate of electric charge by the length of the wire, the total charge in the wire and the velocity of those charges can be accounted for. The equation to find the force on a wire becomes: F = ILBsinθ Notice the similarities between this equation and that for a single particle moving through a magnetic field. Both utilize the sine function, indicating that like an individual particle, a wire that is aligned parallel to a magnetic field will not experience a force. The maximum force experienced by the wire will occur when the wire is perpendicular to the magnetic field.

5 Practice Problem 2: What is the magnitude and direction of a force on a 50 cm long wire carrying a current of 3 amps from left to right, if it is placed in a 0.4 T magnetic field which is oriented South to North? Electromagnetism In 1819, Hans Oersted observed that an electric current in a wire causes a compass needle to deflect. He deduced that a current carrying conductor produces a magnetic field. The strength of the magnetic field produced by a straight current carrying conductor can be calculated using the equation: B = µ 0I/2πr (This equation is for Honors only) In the above equation, µ 0 is a constant known as the permeability of free space (4π x 10-7 ), I is the current, and r is the distance from wire. To find the direction of the magnetic field, B, in a current carrying wire, we need another version of the Right Hand Rule, often called the Right Hand Source Rule. Imagine you are grasping the wire with your right hand with your thumb point upwards in the direction of the current. Your fingers will naturally curl in the direction of B. The strength of the magnetic field can be further increased by forming a loop out of the wire, as the magnetic field produced by one side of the wire is now condensed inside the loop. The region inside the loop has a significantly stronger magnetic field than the wire had when it was straight, even with the same current running through it. The magnetic field inside a current carrying loop can be calculated with the following equation: B = µ 0I/2R (Equation for Honors only) In the above equation, R represents the radius of the loop. The magnetic field inside the loop can further be enhanced by making multiple loops, as long as a continuous wire is used and all loops are formed in the same direction. A long straight wire bent into a coil of closely spaced loops is known as a solenoid. The region in the center of a solenoid has a very strong magnetic field, due to the many loops that are stacked together, each producing a magnetic field. If an iron rod is placed through the loop, it can become magnetized as well, creating what is known as an electromagnet. It is important to realize that the loops only produce the magnetic field when a current is actually flowing. Once the current stops (i.e. the circuit is broken), the wire will no longer produce a magnetic field.

6 Overview of Electromagnetism Oersted s demonstration that current could produce magnetism would have far reaching effects. Scientists rushed to discover if the inverse was true could magnetism produce current? It would take ten years before Michael Faraday was able to show that it was indeed possible. Appreciate that we have three quantities of interest magnetic force, magnetic fields and current. The production of each of these has very important consequences. In summary, 1) Oerstad showed you can create magnetic fields, B, from current, I. An application is the above solenoid, often call an electromagnet. (Creating B from I). 2) Faraday showed next that it is possible to create magnetic force from magnetic fields and current. (Creating F from B and I). The major application here is the motor. 3) Lastly, it was shown that one could create current from magnetic fields and magnetic forces. (Creating I from F and B). The major application now is the generator. More information about Faraday, motors and generators follows below. Application: Motors We have already established that when a current carrying wire is placed in a magnetic field, it experiences a magnetic force. When a current carrying wire is arranged into a loop and placed in a magnetic field, it will cause a net torque on the loop. Although current only flows in one direction through a wire, when the wire is bent into a loop, the current will effectively be flowing in two directions relative to the magnetic field. For instance, in the diagram to the right, the current is flowing up bottom to top on the left side of the loop, and down, top to bottom on the right side of the loop. Following the Right Hand Rule, the left part of the loop experiences a force into the page, and the right side experiences a force out of the page. If this loop is free to pivot around an axle in the middle, it will start to rotate due to the applied torque (a perpendicular force is applied at a distance away from the axis of rotation). The spinning axle now has the potential to do mechanical work. This is the theory behind an electric motor.

7 Electromagnetic Induction While Oersted s observation made an important connection between electricity and magnetism, perhaps a more significant discovery was made by Michael Faraday. Faraday realized that if an electric current could produce a magnetic field, the opposite is also true, in that a changing magnetic field can produce a current in a wire. The process of creating a current in a wire using a magnetic field is known as electromagnetic induction. The experiment in which Faraday made this observation is illustrated in the diagram below. On the left side of the diagram, a battery is used to produce a current in a wire. There is a switch included so that the current on the left circuit can be stopped and started as needed. The wire is wrapped around one side of an iron ring. A separate wire is wrapped around the other side of the iron ring. This wire is connected to an ammeter which measures the current in the wire, similar to the multimeter we used in class.

8 Since the circuit on the right is not directly connected to the circuit on the left, it was not expected that the ammeter would measure any current, even when the switch was closed. However, as soon as the switch closed, the ammeter measured a slight current, and then went back to zero. When the switch was opened again, and the current in the left hand circuit stopped flowing, a current was briefly measured flowing in the opposite direction as before, but then it again returned to zero. If the switch was left opened or closed for a long time in the left hand circuit, no current would be measured in the circuit on the right. Faraday realized that when current in the left hand circuit produces a magnetic field, the iron core will become magnetized. As the strength of the magnetic field around the core was changing, a current could be measured in the circuit on the right. Once the core was fully magnetized and the magnetic field was stable, there was no longer any current. As the left circuit was disconnected, the magnetic field in the core decreased, producing a slight current in the circuit on the right. Once the core was fully demagnetized, there was no longer a measurable current in the right hand circuit. The apparent conclusion from this experiment is that a changing magnetic field will produce a current in a wire. A magnetic field that is steady and unchanging will not yield any current in the wire. Faraday s conclusions to this, and other experiments, is summarized in Faraday s Law, which states that the induced voltage in a coil is proportional to the product of the number of loops and the rate at which the magnetic field changes within those loops. Remember that there is a distinct difference between voltage (electric pressure) and current. While the voltage applied to the coil depends on the factors above, the current that results from this voltage also depends on the resistance in the wire. Take the example of a copper coil and a rubber coil, each with the same number of loops. If a magnet is moved in and out of both coils, an equal voltage will be induced in both coils. However, since the rubber coil has a very high resistance, virtually no current will flow through it, while the copper coil could have a measurable current. For the remainder of this discussion, we will assume a conductive coil is being used, so when a voltage is produced, a current will result. A greater voltage, and therefore current will be induced in a coil with more wires, as seen in the diagram below.

9 There are three common ways that a coil can experience a change in the magnetic field to produce a current. The first is when the strength of the magnetic field varies. In Faraday s experiment, the iron core produced a strong magnetic field when the current was on in the left hand coil, and no magnetic field when the current was off. The process of changing from no magnetic field to a strong magnetic field, or vice versa, is what produced the current in the right hand coil. When the magnetic field had a constant strength, no current was produced. The second method to change the magnetic field is physically moving the coil relative to the magnetic field. If a magnet moves through a coil, or the coil moves through a stationary magnetic field (by moving closer or farther from a magnet), the coil could experience a change in the magnetic field. Notice in the figure below that it doesn t matter if the magnet or the coil is the object in motion. As long as there is relative motion between them which causes the coil to experience a change in the magnetic field, a current can be induced. The final method to change the effective strength of the magnetic field on a coil is to rotate the coil through the magnetic field. The theory behind this depends on the fact that the density of magnetic field lines indicates the strength of the magnetic field. When the loops of a coil are perpendicular to the magnetic field (diagram a below), the greatest number of magnetic field lines will go through the loops, indicating the magnetic field is having the greatest influence on the coil. As the coil rotates in the field (diagram b), fewer field lines will go through the loops, and the affect of the magnetic field decreases. At the point when the loops are parallel to the magnetic field (diagram c), no magnetic field lines are going through the coil, so there is no magnetic influence on the coil. If the coil continues to rotate in the same direction, more field lines will again be going through the loop, until the loop is

10 perpendicular again (diagram e), at which point the coil is experiencing the maximum magnetic field. This change from maximum strength at perpendicular, to no magnetic field, back to maximum strength again can induce a current through the coil. This final method of inducing a current in a coil is often the method used in producing electric current using a generator, as discussed in the next section. It should be noted that there is a fourth method to change the magnetic field in a coil, though it is less practical for most applications. If the size of the coil is reduced while it is in a magnetic field, fewer field lines will be going through the loops, indicating that the coil experiences a decrease in the magnetic field. If the loop is made larger, more field lines go through, indicating that more of the magnetic field is acting on the coil. A current will be induced in a coil when the loops of that coil are changing size, due to this change in the effective magnetic field. Application: AC Generator If a motor can be used to mechanical power using an electric current through a motor, than the reverse process is also possible, in that mechanical power can be used to produce an electric current. The tool used to do so is known as an electric generator. Electric generators use various forms of mechanical work to rotate a wire loop through a magnetic field. As the loop is rotated through the field, an electric current is forced through the wire. One example of this would be a hydro electric power plant. The

11 potential energy stored in water at a high elevation is used to exert a force on the blades of a turbine. Since the turbine is fixed to an axle, the force applied by the water produces a torque, which turns the axle. Inside the generator, the axle is attached to coils of wire, which are positioned between the opposite poles of two permanent magnets. As the coils rotate through the magnetic field, a current is forced through the wire. Another example is a coal powered generator. The coal is burned and the heat from the resulting flame is used to convert water into steam. The pressure forces the steam through the blades, which turns the axle of the generator. A simple model of a generator can be seen in the figure below. As the coil loop rotates through the magnetic field, it should not surprise you that the direction of the current will change depending on the angle of the wire coil. When the loop is perpendicular to the magnetic field, no current is induced in the wire. As the coil rotates through a quarter turn (so coil is now parallel), a positive voltage will be induced in the wire. After another quarter turn, the coil is perpendicular again, so no voltage is produced. Turning through another quarter rotation brings the coil parallel to the magnetic field once again, this time inducing a negative voltage. As the voltage changes from positive to negative, the resulting current will also change directions. The generator has created an alternating current (AC), where the direction of charge is constantly reversing as the coil rotates through the magnetic field. Application: DC Generator Sometimes it is desirable to produce a direct current (DC) rather than an alternating current. To do so, it is necessary to account for the fact that each time the coil has rotated 180 degrees, the current will be changing direction. A commutator is a component that can be attached to the axle of the generator that acts as a conductor between the coil and the wire of the

12 connected circuit. If the wires connected directly to the coil, they would twist around the axle, preventing the generator from rotating freely. Having a conductive ring around the axle allows the current to flow from the axle into attached wires without twisting. This is particularly useful for producing direct current, as the conductive ring can be split into two pieces, as seen in the diagram to the right. The ends of the coil will make contact with alternating sides of the commutator during each half rotation. At the same time, the current in the coil is alternating directions with each half rotation. The net effect is that the current will always be flowing through the connected wire in the same direction, which is a direct current. A Deeper Look At Magnetism At the atomic level, the region of space outside of the nucleus where an electron is most likely to be found is known as an orbital. Up to two electrons may occupy each orbital, but they spin in opposite directions (one clockwise, the other counter clockwise). As a charge moves through space, it produces a magnetic field. We will explore later how the direction of the charge specifically influences the magnetic field. At this point, it is sufficient to say that since the two electrons in a single orbital are spinning in opposite directions, they create opposing magnetic fields, which cancel out. In atoms where there is a single unpaired electron in an orbital, a magnetic field is only produced in one direction (there is no second field to cancel it out). As a result, that atom produces a small magnetic field. On the macro level (looking at a whole sample of a substance, not just a single atom), the ordering of the atoms is randomized. This means that the magnetic field from one atom is pointing in a different direction than another atom. Generally, the magnetic fields from all of the atoms in a substance point in many different directions, and essentially cancel each other out. This is why an overall magnetic force is not observable for most materials. However, when a material with unpaired electrons (such as Iron) is exposed to a magnetic field, the electrons will align their spin to produce a magnetic field in the same orientation as the external field. When multiple electrons align their spin in the same direction, it is known as a magnetic domain. The majority of materials have very limited magnetic properties, but a few are able to retain their magnetism for longer periods of time. Iron, nickel, and cobalt (and their alloys) are able to form strong permanent magnets. Of these, iron is considered a soft magnet, in that it is easy to magnetize it, but it loses magnetism easily. Cobalt and nickel are hard magnets, as they are more difficult to magnetize, but once magnetized, stay magnetized well. Heating up any magnet will effectively reset its magnetic qualities, since the particles in the material vibrate more as they gain energy, and will randomize the direction of the individual electron s magnetic fields.

13 Practice Problem Solutions Practice Problem 1. Use F = qvbsinθ F = (1.6 x C)(20,000 m/s) (0.7 T) =2.24 x N To determine the direction, use the Right Hand Rule. Point your fingers in the direction of the velocity (up the desk away from you), curl them in the direction of the magnetic field (to the right), and your thumb points in direction of the magnetic force. The particle moves down, into the desk. Practice Problem 2. Use F = ILBsinθ F = (3 A)(.5 m)(0.4 T) sin(90) = 0.6 N up (out of page) Point your fingers to the right, curl them away from you to the north (top of page). Your thumb is now pointing up, out of the page.

> What happens when the poles of two magnets are brought close together? > Two like poles repel each other. Two unlike poles attract each other.

> What happens when the poles of two magnets are brought close together? > Two like poles repel each other. Two unlike poles attract each other. CHAPTER OUTLINE Section 1 Magnets and Magnetic Fields Key Idea questions > What happens when the poles of two magnets are brought close together? > What causes a magnet to attract or repel another magnet?

More information

CHAPTER 20 Magnetism

CHAPTER 20 Magnetism CHAPTER 20 Magnetism Units Magnets and Magnetic Fields Electric Currents Produce Magnetic Fields Force on an Electric Current in a Magnetic Field; Definition of B Force on Electric Charge Moving in a Magnetic

More information

Chapter 18 Study Questions Name: Class:

Chapter 18 Study Questions Name: Class: Chapter 18 Study Questions Name: Class: Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. The region around a magnet in which magnetic forces

More information

Chapter 21. Magnetism

Chapter 21. Magnetism Chapter 21 Magnetism Magnets Poles of a magnet are the ends where objects are most strongly attracted Two poles, called north and south Like poles repel each other and unlike poles attract each other Similar

More information

Magnets & Magnetic Fields

Magnets & Magnetic Fields Magnets & Magnetic Fields Magnets Magnets have 2 poles, North and South if broken in half, each half will have both poles at the ends. Like poles repel, unlike poles attract. Hard Magnets- materials that

More information

Torque on a Current Loop

Torque on a Current Loop Today Chapter 19 Magnetism Torque on a current loop, electrical motor Magnetic field around a current carrying wire. Ampere s law Solenoid Material magnetism Clicker 1 Which of the following is wrong?

More information

Chapter 19. Magnetism

Chapter 19. Magnetism Chapter 19 Magnetism The figure shows the path of a negatively charged particle in a region of a uniform magnetic field. Answer the following questions about this situation (in each case, we revert back

More information

Section 3: Mapping Magnetic Fields. In this lesson you will

Section 3: Mapping Magnetic Fields. In this lesson you will Section 3: Mapping Magnetic Fields In this lesson you will state the Law(s) of magnetic forces use iron filings to map the field around various configurations of bar magnets and around a horse shoe magnet

More information

Chapter 17: Magnetism

Chapter 17: Magnetism Chapter 17: Magnetism Section 17.1: The Magnetic Interaction Things You Already Know Magnets can attract or repel Magnets stick to some things, but not all things Magnets are dipoles: north and south Labels

More information

NCERT solutions Magnetic effects of current (In-text questions)

NCERT solutions Magnetic effects of current (In-text questions) NCERT solutions Magnetic effects of current (In-text questions) Page No: 224 Question 1 Why does a compass needle get deflected when brought near a bar magnet? Compass needle is a small permanent magnet.

More information

PHYS:1200 LECTURE 27 ELECTRICITY AND MAGNETISM (5)

PHYS:1200 LECTURE 27 ELECTRICITY AND MAGNETISM (5) 1 PHYS:1200 LECTURE 27 ELECTRICITY AND MAGNETISM (5) Everyone has played with magnets and knows that they stick to some materials and not to others. This lecture explores the physical principles behind

More information

Magnetism. (Unit Review)

Magnetism. (Unit Review) Physics Name: Date: Period: Magnetism (Unit Review) Coronal mass ejection Diamagnetic Differential rotation Electric motor Electromagnet Electromagnetic induction Faraday s Law of Induction Galvanometer

More information

MODULE 4.2 MAGNETISM ELECTRIC CURRENTS AND MAGNETISIM VISUAL PHYSICS ONLINE

MODULE 4.2 MAGNETISM ELECTRIC CURRENTS AND MAGNETISIM VISUAL PHYSICS ONLINE VISUAL PHYSICS ONLINE MODULE 4.2 MAGNETISM ELECTRIC CURRENTS AND MAGNETISIM When electric charges are in motion they exert forces on each other that can t be explained by Coulomb s law. If two parallel

More information

A little history. Electricity and Magnetism are related!

A little history. Electricity and Magnetism are related! Intro to Magnetism A little history Until the early 19 th century, scientists thought electricity and magnetism were unrelated In 1820, Danish science professor Hans Christian Oersted was demonstrating

More information

Kirchhoff s rules, example

Kirchhoff s rules, example Kirchhoff s rules, example Magnets and Magnetism Poles of a magnet are the ends where objects are most strongly attracted. Two poles, called north and south Like poles repel each other and unlike poles

More information

Unit Packet Table of Contents Notes 1: Magnetism Intro Notes 2: Electromagnets Notes 3: Electromagnetic Induction Guided Practice: Left Hand Rule #3

Unit Packet Table of Contents Notes 1: Magnetism Intro Notes 2: Electromagnets Notes 3: Electromagnetic Induction Guided Practice: Left Hand Rule #3 Unit Packet Table of Contents Notes 1: Magnetism Intro Notes 2: Electromagnets Notes 3: Electromagnetic Induction Guided Practice: Left Hand Rule #3 Name Date Notes: Magnetism intro. Regents Physics Objectives:

More information

Magnetism. and its applications

Magnetism. and its applications Magnetism and its applications Laws of Magnetism 1) Like magnetic poles repel, and 2) unlike poles attract. Magnetic Direction and Strength Law 3 - Magnetic force, either attractive or repelling varies

More information

MODULE 6 ELECTROMAGNETISM MAGNETIC FIELDS MAGNETIC FLUX VISUAL PHYSICS ONLINE

MODULE 6 ELECTROMAGNETISM MAGNETIC FIELDS MAGNETIC FLUX VISUAL PHYSICS ONLINE VISUAL PHYSICS ONLINE MODULE 6 ELECTROMAGNETISM MAGNETIC FIELDS MAGNETIC FLUX Magnetic field (-field ): a region of influence where magnetic materials and electric currents are subjected to a magnetic

More information

Reading Question 24.1

Reading Question 24.1 Reading Question 24.1 A compass in a magnetic field will line up A. With the north pole pointing in the direction of the magnetic field. B. With the north pole pointing opposite the direction of the magnetic

More information

Gravity Electromagnetism Weak Strong

Gravity Electromagnetism Weak Strong 19. Magnetism 19.1. Magnets 19.1.1. Considering the typical bar magnet we can investigate the notion of poles and how they apply to magnets. 19.1.1.1. Every magnet has two distinct poles. 19.1.1.1.1. N

More information

Electromagnetism Notes 1 Magnetic Fields

Electromagnetism Notes 1 Magnetic Fields Electromagnetism Notes 1 Magnetic Fields Magnets can or other magnets. They are able to exert forces on each other without touching because they are surrounded by. Magnetic Flux refers to Areas with many

More information

Magnetic Fields and Forces

Magnetic Fields and Forces Nicholas J. Giordano www.cengage.com/physics/giordano Chapter 20 Magnetic Fields and Forces Marilyn Akins, PhD Broome Community College Magnetism Magnetic fields are produced by moving electric charges

More information

EB Education Revision Guide. How to work with Magnetism and Electromagnetism

EB Education Revision Guide. How to work with Magnetism and Electromagnetism EB Education Revision Guide How to work with Magnetism and Electromagnetism Magnets Magnetic fields Magnets have two poles, north and south. They produce a magnetic field, this is a region where other

More information

ELECTROMAGNETISM The study of the relationship between electricity and magnetism is called

ELECTROMAGNETISM The study of the relationship between electricity and magnetism is called ELECTROMAGNETISM The study of the relationship between electricity and magnetism is called Electromagnetism Before, 1819 it was believed that there was no connection between electricity and magnetism.

More information

Vocabulary. Magnet. a material that can create magnetic effects by itself. Electromagnet

Vocabulary. Magnet. a material that can create magnetic effects by itself. Electromagnet Vocabulary Term Magnet Definition a material that can create magnetic effects by itself Electromagnet Magnets created by electric current flowing in wires. A simple electromagnet is a coil of wire wrapped

More information

Chapter 12. Magnetism and Electromagnetism

Chapter 12. Magnetism and Electromagnetism Chapter 12 Magnetism and Electromagnetism 167 168 AP Physics Multiple Choice Practice Magnetism and Electromagnetism SECTION A Magnetostatics 1. Four infinitely long wires are arranged as shown in the

More information

Magnetism. a) Ferromagnetic materials are strongly attracted to magnets. b) Paramagnetic materials are weakly attracted to magnets

Magnetism. a) Ferromagnetic materials are strongly attracted to magnets. b) Paramagnetic materials are weakly attracted to magnets Magnetism Types of Magnetic Materials Magnetic substances can be classified into three basic groups, according to their response to a magnet. Note the strength and direction of the interaction. a) Ferromagnetic

More information

Magnets. Magnetic vs. Electric

Magnets. Magnetic vs. Electric Magnets A force is applied to the iron filings causing them to align themselves to the direction of the magnetic field. A compass needle will tell you the direction of the field. Show Fields of little

More information

HIGH SCHOOL SCIENCE. Physical Science 7: Electricity & Magnetism

HIGH SCHOOL SCIENCE. Physical Science 7: Electricity & Magnetism HIGH SCHOOL SCIENCE Physical Science 7: Electricity & Magnetism WILLMAR PUBLIC SCHOOL 2013-2014 EDITION CHAPTER 7 Electricity & Magnatism In this chapter you will: 1. Analyze factors that affect the strength

More information

Section 11: Magnetic Fields and Induction (Faraday's Discovery)

Section 11: Magnetic Fields and Induction (Faraday's Discovery) Section 11: Magnetic Fields and Induction (Faraday's Discovery) In this lesson you will describe Faraday's law of electromagnetic induction and tell how it complements Oersted's Principle express an understanding

More information

Electric Charge. Conductors A material that transfers charge easily Metals

Electric Charge. Conductors A material that transfers charge easily Metals Electric Charge An electrical property of matter that creates a force between objects. Like charges repel Opposite charges attract Equal amount of positive and negative = no net charge Electrons: Negative

More information

Section 11: Magnetic Fields and Induction (Faraday's Discovery)

Section 11: Magnetic Fields and Induction (Faraday's Discovery) Section 11: Magnetic Fields and Induction (Faraday's Discovery) In this lesson you will describe Faraday's law of electromagnetic induction and tell how it complements Oersted's Principle express an understanding

More information

Physics Week 5(Sem. 2) Name. Magnetism. Chapter Summary. Magnetic Fields

Physics Week 5(Sem. 2) Name. Magnetism. Chapter Summary. Magnetic Fields Physics Week 5(Sem. 2) Name Chapter Summary Magnetism Magnetic Fields Permanent magnets have long been used in navigational compasses. The needle in a compass is supported to allow it to freely rotate

More information

General Physics II. Magnetic Fields and Forces

General Physics II. Magnetic Fields and Forces General Physics II Magnetic Fields and Forces 1 Magnetism Magnetism underlies the operation of the hard disk drive, which is the mainstay of modern electronic information storage, from computers to ipods.

More information

36 Magnetism. A moving electric charge is surrounded by a magnetic field.

36 Magnetism. A moving electric charge is surrounded by a magnetic field. A moving electric charge is surrounded by a magnetic field. Electricity and magnetism were regarded as unrelated phenomena until it was noticed that an electric current caused the deflection of the compass

More information

Chapter 22, Magnetism. Magnets

Chapter 22, Magnetism. Magnets Chapter 22, Magnetism Magnets Poles of a magnet (north and south ) are the ends where objects are most strongly attracted. Like poles repel each other and unlike poles attract each other Magnetic poles

More information

A moving electric charge is surrounded by a magnetic field Magnetic Poles

A moving electric charge is surrounded by a magnetic field Magnetic Poles A moving electric charge is surrounded by a magnetic field. Electricity and magnetism were regarded as unrelated phenomena until it was noticed that an electric current caused the deflection of the compass

More information

General Physics II. Magnetism

General Physics II. Magnetism General Physics II Magnetism Bar magnet... two poles: N and S Like poles repel; Unlike poles attract. Bar Magnet Magnetic Field lines [B]: (defined in a similar way as electric field lines, direction and

More information

Some History of Magnetism

Some History of Magnetism Magnetism Some History of Magnetism The ancient Greeks were the first to observe magnetism. They studied the mineral magnetite. The poles of a magnet were observed to be south or north seeking. These properties

More information

PHYSICS. Chapter 29 Lecture FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E RANDALL D. KNIGHT

PHYSICS. Chapter 29 Lecture FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E RANDALL D. KNIGHT PHYSICS FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E Chapter 29 Lecture RANDALL D. KNIGHT Chapter 29 The Magnetic Field IN THIS CHAPTER, you will learn about magnetism and the magnetic field.

More information

Chapter 19. Magnetism. 1. Magnets. 2. Earth s Magnetic Field. 3. Magnetic Force. 4. Magnetic Torque. 5. Motion of Charged Particles. 6.

Chapter 19. Magnetism. 1. Magnets. 2. Earth s Magnetic Field. 3. Magnetic Force. 4. Magnetic Torque. 5. Motion of Charged Particles. 6. Chapter 19 Magnetism 1. Magnets 2. Earth s Magnetic Field 3. Magnetic Force 4. Magnetic Torque 5. Motion of Charged Particles 6. Amperes Law 7. Parallel Conductors 8. Loops and Solenoids 9. Magnetic Domains

More information

Physics 17 Part M Dr. Alward

Physics 17 Part M Dr. Alward Physics 17 Part M Dr. Alward Elementary Facts Concerning Magnets Magnets have north and south poles. Like Poles Repel Unlike Poles Attract Magnetic Dipoles Magnets have two poles, one north, the other

More information

Magnets attract some metals but not others

Magnets attract some metals but not others Electricity and Magnetism Junior Science Magnets attract some metals but not others Some objects attract iron and steel. They are called magnets. Magnetic materials have the ability to attract some materials

More information

Name: Class: Date: AP Physics Spring 2012 Q6 Practice. Multiple Choice Identify the choice that best completes the statement or answers the question.

Name: Class: Date: AP Physics Spring 2012 Q6 Practice. Multiple Choice Identify the choice that best completes the statement or answers the question. ame: Class: Date: ID: A AP Physics Spring 2012 Q6 Practice Multiple Choice Identify the choice that best completes the statement or answers the question. 1. (2 points) A potential difference of 115 V across

More information

PHY 1214 General Physics II

PHY 1214 General Physics II PHY 1214 General Physics II Lecture 15 Magnetic Fields and Forces June 28, 2005 Weldon J. Wilson Professor of Physics & Engineering Howell 221H wwilson@ucok.edu Lecture Schedule (Weeks 4-6) We are here.

More information

Magnetism & Electromagnetism

Magnetism & Electromagnetism Magnetism & Electromagnetism By: Dr Rosemizi Abd Rahim Click here to watch the magnetism and electromagnetism animation video http://rmz4567.blogspot.my/2013/02/electrical-engineering.html 1 Learning Outcomes

More information

Physics 12. Unit 8 Magnetic Field and Electromagnetism Part I

Physics 12. Unit 8 Magnetic Field and Electromagnetism Part I Physics 12 Unit 8 Magnetic Field and Electromagnetism Part I 1. Basics about magnets Magnets have been known by ancient people since long time ago, referring to the iron-rich rocks, called magnetite or

More information

So far. Chapter 19. Today ( ) Magnets. Types of Magnetic Materials. More About Magnetism 10/2/2011

So far. Chapter 19. Today ( ) Magnets. Types of Magnetic Materials. More About Magnetism 10/2/2011 So far Chapter 19 Magnetism Electrostatics, properties of stationary charges Coulomb s law Electric field, electric potential Capacitors Ohm s law and resistance Today (19.1-19.4) Magnets Magnetism Earth

More information

Chapter 27, 28 & 29: Magnetism & Electromagnetic Induction

Chapter 27, 28 & 29: Magnetism & Electromagnetic Induction Chapter 27, 28 & 29: Magnetism & Electromagnetic Induction The Magnetic Field The Magnetic Force on Moving Charges The Motion of Charged Particles in a Magnetic Field The Magnetic Force Exerted on a Current-Carrying

More information

Chapter 4: Magnetic Field

Chapter 4: Magnetic Field Chapter 4: Magnetic Field 4.1 Magnetic Field 4.1.1 Define magnetic field Magnetic field is defined as the region around a magnet where a magnetic force can be experienced. Magnetic field has two poles,

More information

Topic 6.3 Magnetic Force and Field. 2 hours

Topic 6.3 Magnetic Force and Field. 2 hours Topic 6.3 Magnetic Force and Field 2 hours 1 Magnetic Fields A magnetic field is said to exist at a point if a compass needle placed there experiences a force. The appearance of a magnetic field can be

More information

Answer Notes Marks 1 (a) (i) arrows on two or more {lines from N to S and/or clockwise on loops around wire}; pointing to the left;

Answer Notes Marks 1 (a) (i) arrows on two or more {lines from N to S and/or clockwise on loops around wire}; pointing to the left; 1 (a) (i) arrows on two or more {lines from N to S and/or clockwise on loops around wire}; accept arrows beside lines 1 showing correct directions reject contradicting arrows (i.e. one correct and one

More information

Magnetic Force http://www-spof.gsfc.nasa.gov/education/imagnet.html The ancient Greeks, originally those near the city of Magnesia, and also the early Chinese knew about strange and rare stones (possibly

More information

Magnets & Electromagnets. Pg

Magnets & Electromagnets. Pg Magnets & Electromagnets Pg. 378-385 Permanent Magnets 1. Where is the magnetic field the strongest? At the poles! **the magnetic field lines of a bar magnet are similar to the electric field lines of

More information

Eddy currents. Applications of electromagnetic induction

Eddy currents.   Applications of electromagnetic induction Faraday's Law of Electromagnetic Induction Whenever the magnetic fireld in the region of a conductor is moving, or changing in magnitude, electrons are induced to flow through the conductor. Mutual Induction

More information

College Physics B - PHY2054C

College Physics B - PHY2054C College - PHY2054C 09/22/2014 My Office Hours: Tuesday 10:00 AM - Noon 206 Keen Building Outline 1 2 3 When current passes through one resistor and then another, the resistors are said to be in series:

More information

Electromagnetism. Kevin Gaughan for. Bristol Myers Squibb

Electromagnetism. Kevin Gaughan for. Bristol Myers Squibb Electromagnetism Kevin Gaughan for Bristol Myers Squibb Contents Magnets and Ferromagnetism Domains Theory H, B and µ The links between electricity and Magnetism Electromagnets Induction Applications of

More information

Magnetism & EM Induction

Magnetism & EM Induction Physics Traditional 1314 Williams Magnetism & EM Induction Chapters 19,20 2 Magnetism Notes Moving charges are the source of all magnetism. Since the smallest charge which can eist is an electron, and

More information

Magnetic Forces and Fields (Chapters 29-30)

Magnetic Forces and Fields (Chapters 29-30) Magnetic Forces and Fields (Chapters 29-30) Magnetism Magnetic Materials and Sources Magnetic Field, Magnetic Force Force on Moving Electric Charges Lorentz Force Force on Current Carrying Wires Applications

More information

4.7 Magnetism and electromagnetism

4.7 Magnetism and electromagnetism 4.7 Magnetism and electromagnetism Electromagnetic effects are used in a wide variety of devices. Engineers make use of the fact that a magnet moving in a coil can produce electric current and also that

More information

Calculus Relationships in AP Physics C: Electricity and Magnetism

Calculus Relationships in AP Physics C: Electricity and Magnetism C: Electricity This chapter focuses on some of the quantitative skills that are important in your C: Mechanics course. These are not all of the skills that you will learn, practice, and apply during the

More information

MAGNETIC FIELDS. - magnets have been used by our species for thousands of years. - for many of these years we had no clue how they worked:

MAGNETIC FIELDS. - magnets have been used by our species for thousands of years. - for many of these years we had no clue how they worked: MAGNETIC FIELDS A SHORT HISTORY OF MAGNETS: - magnets have been used by our species for thousands of years - for many of these years we had no clue how they worked: 200 BC an ancient civilization in Asia

More information

ì<(sk$m)=beabid< +^-Ä-U-Ä-U

ì<(sk$m)=beabid< +^-Ä-U-Ä-U Physical Science by Lillian Duggan Genre Comprehension Skill Text Features Science Content Nonfiction Sequence Captions Charts Diagrams Glossary Forms of Energy Scott Foresman Science 6.17 ì

More information

Continuing the Analogy. Electricity/Water Analogy: PHY205H1F Summer Physics of Everyday Life Class 8: Electric Current, Magnetism

Continuing the Analogy. Electricity/Water Analogy: PHY205H1F Summer Physics of Everyday Life Class 8: Electric Current, Magnetism PHY205H1F ummer Physics of Everyday Life Class 8: Electric Current, Magnetism Flow of Charge Voltage, Current, Resistance Ohm s Law DC and AC Electric Power Light bulbs Electric Circuits Magnetic Force

More information

Electricity and Magnetism

Electricity and Magnetism Electricity and Magnetism S8P5. Students will recognize the characteristics of gravity, electricity, and magnetism as major kinds of forces acting in nature. b. Demonstrate the advantages and disadvantages

More information

Electromagnetism Review Sheet

Electromagnetism Review Sheet Electromagnetism Review Sheet Electricity Atomic basics: Particle name Charge location protons electrons neutrons + in the nucleus - outside of the nucleus neutral in the nucleus What would happen if two

More information

Lab 7: Magnetism Introduction Magnets need no introduction (i.e. introduction to be added in future revision).

Lab 7: Magnetism Introduction Magnets need no introduction (i.e. introduction to be added in future revision). CSUEB Physics 1780 Lab 7: Magnetism Page 1 Lab 7: Magnetism Introduction Magnets need no introduction (i.e. introduction to be added in future revision). Experiments The purpose of these experiments is

More information

Magnetizing a substance

Magnetizing a substance Magnetism What is a magnet? Any material that has the property of attracting Iron (or steel), Nickel or Cobalt Magnets exert a force on other magnets or particles with an electrical charge Magnets may

More information

Magnetic Fields Permanent Magnets

Magnetic Fields Permanent Magnets 1 Magnetic Fields Permanent Magnets Magnetic fields are continuous loops leaving a North pole and entering a South pole they point in direction that an isolated North would move Highest strength near poles

More information

Displacement Current. Ampere s law in the original form is valid only if any electric fields present are constant in time

Displacement Current. Ampere s law in the original form is valid only if any electric fields present are constant in time Displacement Current Ampere s law in the original form is valid only if any electric fields present are constant in time Maxwell modified the law to include timesaving electric fields Maxwell added an

More information

Slide 1 / 50. Slide 2 / 50. Slide 3 / 50. Electromagnetic Induction and Faraday s Law. Electromagnetic Induction and Faraday s Law.

Slide 1 / 50. Slide 2 / 50. Slide 3 / 50. Electromagnetic Induction and Faraday s Law. Electromagnetic Induction and Faraday s Law. Electromagnetic Induction and Faraday s Law Slide 1 / 50 Electromagnetic Induction and Faraday s Law Slide 2 / 50 Induced EMF Faraday s Law of Induction Lenz s Law EMF Induced in a Moving Conductor Changing

More information

Slide 1 / 50. Electromagnetic Induction and Faraday s Law

Slide 1 / 50. Electromagnetic Induction and Faraday s Law Slide 1 / 50 Electromagnetic Induction and Faraday s Law Slide 2 / 50 Electromagnetic Induction and Faraday s Law Induced EMF Faraday s Law of Induction Lenz s Law EMF Induced in a Moving Conductor Changing

More information

Chapter 24: Magnetic Fields & Forces

Chapter 24: Magnetic Fields & Forces Chapter 24: Magnetic Fields & Forces We live in a magnetic field. The earth behaves almost as if a bar magnet were located near its center. The earth s axis of rotation and Magnetic axis are not the same

More information

Transfer of Forces Classwork

Transfer of Forces Classwork Transfer of Forces Classwork 1. Describe what a force is. 2. List at least four forces that are observed in nature. 3. How are forces transferred between two objects if they are not in contact? 4. Describe

More information

Electricity and Electromagnetism SOL review Scan for a brief video. A. Law of electric charges.

Electricity and Electromagnetism SOL review Scan for a brief video. A. Law of electric charges. A. Law of electric charges. Electricity and Electromagnetism SOL review Scan for a brief video The law of electric charges states that like charges repel and opposite charges attract. Because protons and

More information

Material World Electricity and Magnetism

Material World Electricity and Magnetism Material World Electricity and Magnetism Electrical Charge An atom is composed of small particles of matter: protons, neutrons and electrons. The table below describes the charge and distribution of these

More information

Chapter 29. Magnetic Fields

Chapter 29. Magnetic Fields Chapter 29 Magnetic Fields Outline 29.1 Magnetic Fields and Forces 29.2 Magnetic Force Acting on a Current-Carrying Conductor 29.4 Motion of a Charged Particle in a Uniform Magnetic Field 29.5 Applications

More information

Electricity (& Magnetism)

Electricity (& Magnetism) EA Notes (Scen 101), Tillery Chapter 6 Electricity (& Magnetism) Introduction First five chapters are "Newtonian Physics", mechanical explanations based on Newton's Laws applied to explain the motion of

More information

General Physics (PHYS )

General Physics (PHYS ) General Physics (PHYS ) Chapter 22 Magnetism Magnetic Force Exerted on a current Magnetic Torque Electric Currents, magnetic Fields, and Ampere s Law Current Loops and Solenoids Magnetism in Matter GOT

More information

MAGNETIC EFFECTS OF ELECTRIC CURRENT

MAGNETIC EFFECTS OF ELECTRIC CURRENT CHAPTER 13 MAGETIC EFFECT OF ELECTRIC CURRET In this chapter, we will study the effects of electric current : 1. Hans Christian Oersted (1777-1851) Oersted showed that electricity and magnetism are related

More information

Electromagnetism. Chapter I. Figure 1.1: A schematic diagram of Earth s magnetic field. Sections 20-1, 20-13

Electromagnetism. Chapter I. Figure 1.1: A schematic diagram of Earth s magnetic field. Sections 20-1, 20-13 Chapter I Electromagnetism Day 1 Magnetism Sections 20-1, 20-13 An investigation of permanent magnets shows that they only attract certain metals specifically those containing iron, or a few other materials,

More information

Electromagnetic Induction. Bo Zhou Faculty of Science, Hokudai

Electromagnetic Induction. Bo Zhou Faculty of Science, Hokudai Electromagnetic Induction Bo Zhou Faculty of Science, Hokudai Oersted's law Oersted s discovery in 1820 that there was a close connection between electricity and magnetism was very exciting until then,

More information

4.7.1 Permanent and induced magnetism, magnetic forces and fields. Content Key opportunities for skills development

4.7.1 Permanent and induced magnetism, magnetic forces and fields. Content Key opportunities for skills development 4.7 Magnetism and electromagnetism Electromagnetic effects are used in a wide variety of devices. Engineers make use of the fact that a magnet moving in a coil can produce electric current and also that

More information

PHYS 1442 Section 004 Lecture #14

PHYS 1442 Section 004 Lecture #14 PHYS 144 Section 004 Lecture #14 Wednesday March 5, 014 Dr. Chapter 1 Induced emf Faraday s Law Lenz Law Generator 3/5/014 1 Announcements After class pickup test if you didn t Spring break Mar 10-14 HW7

More information

Lecture PowerPoints. Chapter 20 Physics: Principles with Applications, 6 th edition Giancoli

Lecture PowerPoints. Chapter 20 Physics: Principles with Applications, 6 th edition Giancoli Lecture PowerPoints Chapter 20 Physics: Principles with Applications, 6 th edition Giancoli 2005 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for

More information

6.3 Magnetic Force and Field (4 hr)

6.3 Magnetic Force and Field (4 hr) 6.3 Magnetic Force and Field (4 hr) Name Activity 631 Investigating Magnetic Field around a magnet Activity 632 Investigating Electric Field in a slinky. Activity 633 Build your own Electric Motor. Read

More information

CURRENT-CARRYING CONDUCTORS / MOVING CHARGES / CHARGED PARTICLES IN CIRCULAR ORBITS

CURRENT-CARRYING CONDUCTORS / MOVING CHARGES / CHARGED PARTICLES IN CIRCULAR ORBITS PHYSICS A2 UNIT 4 SECTION 4: MAGNETIC FIELDS CURRENT-CARRYING CONDUCTORS / MOVING CHARGES / CHARGED PARTICLES IN CIRCULAR ORBITS # Questions MAGNETIC FLUX DENSITY 1 What is a magnetic field? A region in

More information

DAY 12. Summary of Topics Covered in Today s Lecture. Magnetic Fields Exert Torques on a Loop of Current

DAY 12. Summary of Topics Covered in Today s Lecture. Magnetic Fields Exert Torques on a Loop of Current DAY 12 Summary of Topics Covered in Today s Lecture Magnetic Fields Exert Torques on a Loop of Current Imagine a wire bent into the shape of a rectangle with height h and width w. The wire carries a current

More information

Magnetism. Permanent magnets Earth s magnetic field Magnetic force Motion of charged particles in magnetic fields

Magnetism. Permanent magnets Earth s magnetic field Magnetic force Motion of charged particles in magnetic fields Magnetism Permanent magnets Earth s magnetic field Magnetic force Motion of charged particles in magnetic fields Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

More information

Note that a current-carrying solenoid produces a dipole field similar to that of a bar magnet. The field is uniform within the coil.

Note that a current-carrying solenoid produces a dipole field similar to that of a bar magnet. The field is uniform within the coil. An electrical current produces a magnetic field that is directed around it. Conventional current is the flow of positive charge. Hence, it is directed from the positive terminal of the power supply, through

More information

DO PHYSICS ONLINE MOTORS AND GENERATORS MAGNETIC FIELDS

DO PHYSICS ONLINE MOTORS AND GENERATORS MAGNETIC FIELDS DO PHYSICS ONLINE MOTORS AND GENERATORS MAGNETIC FIELDS Powerful magnets are essential components in motors and generators. Some electric motors and generators rely upon a combination of a permanent and

More information

Magnetism. Magnets. Section 1

Magnetism. Magnets. Section 1 Magnets More than 2,000 years ago Greeks discovered deposits of a mineral that was a natural magnet. The mineral is now called magnetite. In the twelfth century Chinese sailors used magnetite to make compasses

More information

Lecture #4.4 Magnetic Field

Lecture #4.4 Magnetic Field Lecture #4.4 Magnetic Field During last several lectures we have been discussing electromagnetic phenomena. However, we only considered examples of electric forces and fields. We first talked about electrostatics

More information

MAGNETIC EFFECTS OF ELECTRIC CURRENT

MAGNETIC EFFECTS OF ELECTRIC CURRENT CHAPTER 13 MAETIC EFFECT OF ELECTRIC CURRET 1. Hans Christian Oersted (1777-1851) Oersted showed that electricity and magnetism are related to each other. His research later used in radio, television etc.

More information

Chapter19-Magnetism and Electricity

Chapter19-Magnetism and Electricity Chapter19-Magnetism and Electricity Magnetism: attraction of a magnet for another object. Magnetic poles: north & south ends of a magnet, they exert the strongest forces Like poles repel each other, unlike

More information

a) head-on view b) side view c) side view Use the right hand rule for forces to confirm the direction of the force in each case.

a) head-on view b) side view c) side view Use the right hand rule for forces to confirm the direction of the force in each case. Electromagnetism Magnetic Force on a Wire Magnetic Field around a Bar Magnet Direction of magnetic field lines: the direction that the North pole of a small test compass would point if placed in the field

More information

Magnetic Attraction and Electromagnetism. Spring 2011

Magnetic Attraction and Electromagnetism. Spring 2011 Magnetic Attraction and Electromagnetism Spring 2011 The Nature of Magnetism Magnets are found everywhere doorbells, TV s, computers Magnets were discovered in a region in Greece called.you guessed it

More information

May 08, Magnetism.notebook. Unit 9 Magnetism. This end points to the North; call it "NORTH." This end points to the South; call it "SOUTH.

May 08, Magnetism.notebook. Unit 9 Magnetism. This end points to the North; call it NORTH. This end points to the South; call it SOUTH. Unit 9 Magnetism This end points to the North; call it "NORTH." This end points to the South; call it "SOUTH." 1 The behavior of magnetic poles is similar to that of like and unlike electric charges. Law

More information

General Physics (PHY 2140)

General Physics (PHY 2140) General Physics (PHY 2140) Lecture 8 Electricity and Magnetism 1. Magnetism Application of magnetic forces Ampere s law 2. Induced voltages and induction Magnetic flux http://www.physics.wayne.edu/~alan/2140website/main.htm

More information

Chapter 8. Electricity and Magnetism. Law of Charges. Negative/Positive

Chapter 8. Electricity and Magnetism. Law of Charges. Negative/Positive Chapter 8 Electricity and Magnetism Electricity and Magnetism (1) Electric Charge Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic

More information