# A Review of Circuitry

Size: px
Start display at page:

Transcription

1 1 A Review of Circuitry There is an attractive force between a positive and a negative charge. In order to separate these charges, a force at least equal to the attractive force must be applied to one of them: A B low E p high E p Work = Fd W = E p This force, acting over a distance, does work on the charge that is moved, so the charge receives potential energy. Such work can be done by chemical reactions taking place in a battery or dry cell, or by mechanical forces in a generator. If the negative charge is subsequently released at B, it will move back to position A, releasing energy which is equal to the original work done to move the charge to B. Now consider the inside of a dry cell: When charge is separated between the two electrodes through chemical reactions, an electric field is created between the different charges and the differently charged electrodes. In particular, the electrons that have accumulated at the negative electrode have gained potential energy. If a conducting wire then connects these two electrodes, another electric field is set up in the wire, causing a force to be exerted on every movable charge in the wire, creating electron flow. Electrons now move back through the wire from the negative electrode, or terminal, of the battery to its positive terminal, losing potential energy along the way. A summary of this process is shown in the following diagram.

2 2 shortage of e - excess of e - receives e - from supplies e - to wire + - the wire connecting wire e - removed from copper wire e - from cell are rod at this end added to the rod due to +ive electron flow at this end electrode direction of conventional current flow Note that as the charge moves back through a wire, energy is given off to heaters, light bulbs, motors, buzzers or any other circuit elements that can absorb energy. Pay close attention to the direction arrows: Electron flow refers to the flow of negative charges, repelled from the negative terminal of a chemical cell and attracted to the positive terminal. Conventional current refers to the direction that an imaginary positive test charge would take if placed into the conductor (the same direction as the field E set up in the wire by the potential difference). This convention was first adopted by scientists in the 1800 s, before there was a clear understanding of the sub-atomic structure of the atom. For current flow to occur, an electric circuit must be set up. All circuits require the following: a power supply to give the electrons potential energy. a conductor, which is a material that allows a free-flow of electrons with little resistance). The most common conductors include: metal conductors (e.g., copper, gold, aluminum). ionized gases or liquids (e.g., electrolytic solutions like salt water). A gas discharge tube (such as a CRT that produces an electron beam). a resistor to use the energy. A resistor is a material that resists electron flow and converts electrical energy to some other form of energy. Examples of resistors include motors, heaters, light bulbs, etc.

3 3 The various ways in which electricity can travel from a source throughout a circuit can be represented by a schematic diagram. Common circuit symbols include the following: cell cells in series cells in parallel resistor + variable resistor lamp ammeter voltmeter A V Two types of circuits you should be familiar with are as follows: Series Circuit - A single current path for electron flow; e.g.: Parallel Circuit - more than one current path for electron flow to occur; e.g.:

4 1 Electric Current Electric current is the rate of movement of electric charge. As an equation, I = q t q is the charge, measured in coulombs (C) I is the current measured in amperes, or amps (A), where one ampere = one coulomb/sec Example #1: A 10 ampere current flows through a wire in 60 seconds. Determine: a) The amount of charge that moves in 60 seconds. b) The number of electrons that pass in 60 seconds. (see Circuitry Ex 1 for answer) Example #2: If a current of 5.0 A flows for 20 minutes, what charge was transferred? (see Circuitry Ex 2 for answer) Kirchhoff s Current Law It was German physicist Gustav Robert Kirchhoff who first determined that electrons are conserved. Since electrons have only one path to travel in a series circuit, electric current at all points remains the same. I o I 3 I 2 I 1 I o = I 1 = I 2 = I 3 where I o = the total current in the circuit, as produced by the battery To measure current properly, an ammeter must be placed in series into the circuit. For the above circuit, the device can be placed anywhere along the path, and will display the same current reading, regardless of its location.

5 2 On the other hand, at a parallel connection, the total current flowing into the connection must equal the sum of the currents flowing out of the connection. I o I 1 I 2 I 3 I o = I 1 + I 2 + I 3 Note that when all resistors are equal, current is divided equally through the different paths. Examine the diagram below. An ammeter placed by the battery will display the total current, which in this case is 6 A. An ammeter placed along any parallel path (in series with the device in that path) will only display the current through that path. If all the lamps have the same resistance in the above circuit, then each of the three ammeters placed in the parallel branches will display a current of 2 A ( = 6 A). If the resistors in the diagram are not equal, then other methods can be used (later). Always keep in mind, though that less resistance means a greater flow of electrons.

6 3 From this, Kirchhoff s Current Law was developed: At any connection in an electric circuit, the total current into a connection must equal the total current out of that connection. Example #3: Determine the unknown currents for each of the following circuits. b) a) 6A 3A 4A 3A c) 5A d) 10A 3A e) f) (see Circuitry Ex 3 for answer)

7 1 Potential Difference, or Voltage Because electrons are very small and carry very little energy, it is more useful to describe the work done on a coulomb of charge (recall from electrostatics that one coulomb (C) = 6.24 x electrons). This is the definition of potential difference, or voltage V: V = E p q or E p = q V where V is measured in volts (V) or Joules/coulomb Since the work done to separate charges is positive, the potential difference between the terminals in a cell is also positive. On the other hand, as charges flow through devices contained within a circuit, work is done by the system and the potential difference across each device is negative. Example #4: If a chemical cell gives 600 J of energy to a charge of 50 C, what is the potential difference of this cell? (see Circuitry Ex 4 for answer) Note that in circuitry, the symbol for potential difference (also called voltage) is simply V ; the delta sign is dropped for simplicity. Kirchhoff s Voltage Law Kirchhoff also examined the potential difference in circuits. He found that, from the law of conservation of energy: the sum of the gains and drops in potential energy around any closed circuit path must equal zero, or in any complete circuit loop, the sum of the gains in potential difference (batteries) is equal to the sum of the potential drops (resistors). We can use this general principle to describe voltage rules for both series and parallel circuits: In a simple, one loop series circuit, the voltage drops across the various resistors = the potential difference of the voltage supply. Put another way, the potential difference of the voltage supply V o is equal to the sum of the potential drops across each of the components V 1, V 2, V 3...etc. That is, V o = V 1 + V 2 + V

8 2 In a circuit with parallel circuit paths, the total potential difference across each parallel branch must be equal; that is, V o = V 1 = V 2 = V 3 =... There is a simple skiing analogy that can be used to determine voltage drops at various locations in a circuit: A chairlift (battery) gives skiers (electrons) the gravitational potential to drop down a ski-slope once they have reached the top of the chair. How those skiers get to the bottom depends on the number of runs (circuit paths) available to them and which hills (resistors, light bulbs, etc) they decide to drop down, losing potential along the way. Connecting wires are analogous to horizontal trails that lead skiers to their runs, since electrons lose almost no potential here. Note that all skiers will have dropped their potential once they have reached the bottom of the chair again. From all this, Kirchhoff s Voltage Law was developed: At any connection in an electric circuit, the sum of the potential difference around any closed pathway or loop = 0. To measure the voltage drop or gain across any device in a circuit properly, a voltmeter must be placed in parallel with the device that is being analyzed. The diagram below shows how a voltmeter is attached to correctly measure the potential difference across a 120 V power supply as well as resistor R 1.

9 3 Example #5: Determine the unknown voltages for each of the following circuits. 12V a) b) 30V c) 3V 28V e) f) d) 36V 8V (see Circuitry Ex 5 for answer)

10 1 Ohm s Law This famous formula results from attempts to find a math relationship relating potential difference to current flow. Recall the Ohm s Law lab from physics 11. In it, you are to apply different voltages across a given resistor and measure the changing current flow. Graphing V vs. I we get the graph that follows: pot l The straight line through the origin difference expresses a direct relationship, so long as V the resistor does not significantly (volts) V overheat. From y = kx + b we get I V = ki current I (amps) By definition, this constant slope represents the resistance R of the circuit element and is measured in ohms (Ω), so that V = IR Note that resistance stays constant only for one temperature; changing temperature changes resistance. Example #6: A small light bulb is connected to 3.0 V and will draw 150 ma. (a) What is the net resistance of the bulb? (b) If the voltage dropped to 2.0 V, how would the current change? (see Circuitry Ex 6 for answer)

11 1 Calculating Resistance in a Circuit We can use Kirchhoff's Laws in combination with Ohm s Law to find the total resistance in circuits. Resistors in Series Consider the diagram below. The voltage law states that V o = V 1 + V 2 + V 3, and the current law states that the current is the same through each resistor. Substituting Ohm's Law into this equation gives: IR o = IR 1 + IR 2 + IR 3 Since the current cancels out on both sides we have the equation for finding the total resistance in series: R o = R 1 + R 2 + R 3 + etc. Example #7: Consider the following circuit diagram showing two resistors attached in series to a battery of two 1.5 V cells. Determine all unknown voltages, currents and resistances for each apparatus in the circuit. V o 1000 oh m s R 1 V = p.d. of c e lls in se r ie s o Since cells connected in series have their voltages added together, the total voltage, 2000 oh m s R 2 V = 2 x 1.5 V o = 3.0 V Some helpful hints: First find the total effect of resistance, R o. This should be listed with the power supply. Second, use Ohm s Law to determine the current I o supplied by the battery. Next, use Kirchhoff s Law to list the current through each resistor. Finally, use Ohm s Law again to find the voltage drop across each resistor; note that the sum of these voltages = V o. (see Circuitry Ex 7 for answer)

12 2 In summary, for a series circuit, V o = V 1 + V etc. (voltage is added) I o = I 1 = I 2 =...etc. (current is the same throughout the circuit) R o = R 1 + R etc. (resistor values are added) Resistors in Parallel Consider this new circuit diagram, showing three resistors in parallel with a power supply of voltage V o. The current law states that current generated at V o will split so that some of the total current I o goes through each resistor. In effect, I o = I 1 + I 2 + I 3. The voltage law states that the voltage drop is the same through each resistor. Substituting Ohm's Law into this equation gives: V R o = V R 1 + V R 2 + V R 3 Since the voltage cancels out on both sides we have the equation for finding the total resistance in series: 1 R o = 1 R R R 3 Example #8: Use your calculator to add these resistors in parallel: (a) 25 Ω, 30 Ω, 50 Ω (b) 50 Ω, 68 Ω, 270 Ω, 569 Ω (see Circuitry Ex 8 for answer)

13 3 Example #9: Consider the following circuit diagram showing two resistors attached in parallel to a battery of two 1.5 V cells. Determine all unknown currents, voltages and resistances. V o 1000 R R 2 oh m s oh m s (see Circuitry Ex 9 for answer) Example #10: In this example R 1 = 5.0 Ω, R 2 =10 Ω and R 3 = 15 Ω and the total current is 10 A. Find the current in each branch. (see Circuitry Ex 10 for answer) In summary, for a parallel circuit, V o = V 1 = V 2 =...etc. I o = I 1 + I etc. 1 R o = 1 R R etc. Also note the following: When resistors are added in series the total resistance is always larger than the largest resistor. When resistors are added in parallel the total resistance is always smaller than the smallest resistor.

14 4 Finally, you have probably noticed that most circuits contain a mixture of resistors in series and in parallel. Such arrangements are called combination circuits. In combination circuits, we want to find: the equivalent resistance for various parts of the circuit; the total resistance Ro in the circuit; the current flow through each device in the circuit; the voltage gain or drop through each device in the circuit. In performing these tasks, you will use a combination of Ohm's Law and Kirchhoff's Laws. Ohm's Law will apply for an entire circuit if the total values are used, or apply to an individual resistor if the individual values are used. The following are the steps to use to solve a combination circuit: Reduce the individual resistor networks to the equivalent of one resistor by applying the appropriate equations. You should now have only a group of series resistors. Redraw the circuit in this simplified way. Determine the missing resistances below: Add these series resistors to get the equivalent of one resistor. Determine this value:

15 5 Find the current in the circuit using Ohm's Law. Finally, work backwards through the circuit using Ohm's Law and/or Kirchhoff's Laws to find the current and voltage across each resistor. Example #11: Complete the table for the circuit on the previous page: R (Ω) V (V) I (A) (see Circuitry Ex 11 for answer) Example #12: Calculate all unknown voltages, currents and resistances for the following circuits: 1.25Ω 16V 2.0Ω 14.0Ω 1.0Ω 2.0Ω 100V 2.25Ω 5.0Ω 7.0Ω 21.0Ω (see Circuitry Ex 12 for answer)

16 1 Calculating Power When electric charges move through a circuit, potential energy is converted to other forms of energy. The rate at which this energy is converted is defined as the power used. As an equation, P = E p t recall from energy unit but also recall that E p = qv so P = qv t and, since q t = I, by substitution we get P = IV This is the general formula for power transformed by any electrical device, measured in watts (W). The rate of energy transformation in a resistance R can also be written in two other ways. By substituting Ohm s Law, P = I 2 R and P = V2 R Example #13: From the circuit diagram for example 11, calculate the power used by each resistor connected in the circuit. (see Circuitry Ex 13 for answer) Since electrical devices use electrical energy, we can find the cost of using electrical devices. However, the basic unit of energy (the joule) is very small for this purpose, so we use a larger unit called the kilowatt hour (kwh). The cost of electricity then is found by: Cost = Energy rate = Pt rate = IVt rate Example #14: Find the cost of operating a kettle for 15 min if it draws 10 A from a standard 120 V outlet, and the cost is 5.5 /kwh. (see Circuitry Ex 14 for answer)

17 2 Example #15: An electric fan draws 2.0 A of current from a 120 V source. Determine the following: (a) the power rating of the fan. (b) its electrical resistance. (c) the cost of operation of the fan during the month of August, assuming it is run continuously and electric energy costs 10 cents per kilowatt hour. (see Circuitry Ex 15 for answer) Finally, note that electrical energy and power can be converted to other forms of energy and power. Electrical energy, which is given by E = Pt (where P = IV), can be equated with: E = Fd E = mg h E = 1 2 m(v f 2 v i 2 ) Example #16: A 6.0 volt motor is used to winch a kg mass a vertical distance of 0.65 m in 5.62 sec. What current will the motor draw? (see Circuitry Ex 16 for answer)

18 1 Terminal Voltage & Internal Resistance In a cell, chemical reactions cause a charge separation to occur between the two terminals. This potential difference is called the Electromotive Force (the term is misleading; it is not a force), often referred to as EMF, with symbol ε and measured in Volts. EMF = the voltage across a supply when there is no current flowing. V T (terminal voltage) = the actual potential difference across the terminals of the supply when a current is being supplied. When a closed circuit is set up so that electrons flow from negative to positive terminals, the terminal voltage drops below EMF value. Here s why: Chemical reactions within the cell cannot separate charges fast enough to keep maximum charge separation. The charges must flow between electrolyte and terminals, and there is always some resistance to this, called internal resistance (r). As a result, when current flows, there is an internal voltage drop equal to ir, and from this, V T = ε - Ir note that when I = 0, V T = ε Examine the following schematic. Note that the small box represents the battery. The terminal voltage V T is measured from one end of the box to the other, and is read by the voltmeter. To find the internal resistance r of the power supply, perform the following steps: ε find the potential difference with the switch open; this is the EMF. Note that the voltmeter can t do this (it draws some current), so other techniques must be used. close switch and measure the potential difference with current flowing (V T ) and measure current with the ammeter.

19 2 EMF - V T = lost voltage (Ir) ε - V T = Ir so r = (ε - V T )/I We can also use use internal and external resistance to find the current supplied by a power source. Start with TV = ε - Ir ε = V T + Ir = IR o + Ir which becomes I = ε/( R o + r) where R o is the total external resistance of the circuit. Example #17: When a 6.0 V EMF battery was connected to a 15 Ω resistance, a current of 375 ma occurred and the voltmeter reading was V. (a) Find the internal resistance r of this supply. (b) If this battery is now connected to a 5.0 Ω resistor, what current will flow? (see Circuitry Ex 17 for answer) Example #18: A battery of EMF 8.0 V and internal resistance r = 1.0 Ω is connected to an external circuit as shown. Find: (a) the equivalent resistance of the circuit. (b) the total current leaving the battery. (c) the potential difference between the terminals of the battery. (see Circuitry Ex 18 for answer)

20 3 Note that the equation V T = ε - Ir can be derived from graphing. Using a variable resistor in the following set-up: V A ammeter reads current voltmeter reads terminal voltage variable resistor changes resistance R o As you would expect, changing the external resistance R o in the circuit changes the current drawn; i.e., more resistance means less current, and vice versa. However, what you might not expect is that the voltage reading V T also changes, due to the changing current. Graphing terminal voltage vs. current: Terminal Voltage (V) Current (A) As current increases, terminal voltage slowly decreases in a linear manner. Using the standard graphing equation y = kx + b, we obtain V T = -ki + b where k is a negative slope Compare this equation with V T = ε - Ir, we see: slope k = internal resistance r y-intercept b = EMF ε This technique is commonly used to find the EMF of any battery or cell.

21 4 Two last points: Consider a small 1.5 V cell connected to a closed circuit with another, much larger power supply that moves electrons from positive to negative terminals in the small cell. In this case, V T is greater than the EMF value, due to the opposite-to-normal flow of current; as a result, V T = ε + Ir In some batteries, this reversed current will cause the chemical reactions to be reversed, effectively recharging the batteries; in other cases, the reactions cannot be reversed due to the chemicals involved. Finally, a complete circuit without an external resistance R o is called a short circuit. Only the internal resistance (r) of the supply limits the flow of current in a short circuit.

### CLASS X- ELECTRICITY

Conductor- Insulator: Materia Materials through which electric current cannot pass are called insulators. Electric Circuit: A continuous a CLASS X- ELECTRICITY als through which electric current can pass

### Electron Theory of Charge. Electricity. 1. Matter is made of atoms. Refers to the generation of or the possession of electric charge.

Electricity Refers to the generation of or the possession of electric charge. There are two kinds of electricity: 1. Static Electricity the electric charges are "still" or static 2. Current Electricity

### ELECTRICITY UNIT REVIEW

ELECTRICITY UNIT REVIEW S1-3-04: How does the Atomic Model help to explain static electricity? 1. Which best describes static electricity? a) charges that can be collected and held in one place b) charges

### Electricity. dronstudy.com

Electricity Electricity is a basic part of our nature and it is one of our most widely used forms of energy. We use electricity virtually every minute of every day for example in lighting, heating, refrigeration,

Forces Read Chapter 7; pages: 191-221 Objectives: - Describe how electrical charges exert forces on each other; Compare the strengths of electric and gravitational forces; Distinguish between conductors

### Name: Class: Date: 1. Friction can result in the transfer of protons from one object to another as the objects rub against each other.

Class: Date: Physics Test Review Modified True/False Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true. 1. Friction can result in

### In this unit, we will examine the movement of electrons, which we call CURRENT ELECTRICITY.

Recall: Chemistry and the Atom! What are the 3 subatomic Where are they found in the particles? atom? What electric charges do they have? How was a positive ion created? How was a negative ion created?

### Test Review Electricity

Name: Date: 1. An operating television set draws 0.71 ampere of current when connected to a 120-volt outlet. Calculate the time it takes the television to consume 3.0 10 5 joules of electric energy. [Show

### Physics Module Form 5 Chapter 2- Electricity GCKL 2011 CHARGE AND ELECTRIC CURRENT

2.1 CHARGE AND ELECTRIC CURRENT Van de Graaf 1. What is a Van de Graaff generator? Fill in each of the boxes the name of the part shown. A device that produces and store electric charges at high voltage

### EXPERIMENT 12 OHM S LAW

EXPERIMENT 12 OHM S LAW INTRODUCTION: We will study electricity as a flow of electric charge, sometimes making analogies to the flow of water through a pipe. In order for electric charge to flow a complete

### Electricity Courseware Instructions

Physics Electricity Courseware Instructions This courseware acts as a supplement to the classroom instruction. The five sections on the following slide link to the topic areas. Following the topic area

### Electric Currents and Circuits

Electric Currents and Circuits Producing Electric Current Electric Current flow of charged particles Need a potential difference to occur Conventional Current- flow of positive charges flowing from positive

### RECALL?? Electricity concepts in Grade 9. Sources of electrical energy Current Voltage Resistance Power Circuits : Series and Parallel

Unit 3C Circuits RECALL?? Electricity concepts in Grade 9. Sources of electrical energy Current Voltage Resistance Power Circuits : Series and Parallel 2 Types of Electricity Electrostatics Electricity

### Continuous flow of electric charges. Current Electricity

Continuous flow of electric charges Current Electricity Did You Know? The voltage across a muscle cell in your body is about 70 millivolts. A millivolt (mv) is one thousandth of a volt. AC and DC DC Direct

### CHAPTER 1 ELECTRICITY

CHAPTER 1 ELECTRICITY Electric Current: The amount of charge flowing through a particular area in unit time. In other words, it is the rate of flow of electric charges. Electric Circuit: Electric circuit

### Electricity Review completed.notebook. June 13, 2013

Which particle in an atom has no electric charge associated with it? a. proton c. neutron b. electron d. nucleus Jun 12 9:28 PM The electrons in a metal sphere can be made to move by touching it with a

### SPH3U1 Lesson 01 Electricity

ELECTRIC CURRENT AND POTENTIAL DIFFERENCE LEARNING GOALS Students will: Define what is meant by electric current. Solve problems involving current, charge and time. Know the difference between electron

### PHYSICS FORM 5 ELECTRICAL QUANTITES

QUANTITY SYMBOL UNIT SYMBOL Current I Amperes A Voltage (P.D.) V Volts V Resistance R Ohm Ω Charge (electric) Q Coulomb C Power P Watt W Energy E Joule J Time T seconds s Quantity of a Charge, Q Q = It

### Chapter 33 - Electric Fields and Potential. Chapter 34 - Electric Current

Chapter 33 - Electric Fields and Potential Chapter 34 - Electric Current Electric Force acts through a field An electric field surrounds every electric charge. It exerts a force that causes electric charges

### Physics Module Form 5 Chapter 2- Electricity GCKL 2011 CHARGE AND ELECTRIC CURRENT

2.1 CHARGE AND ELECTRIC CURRENT Van de Graaf 1. What is a Van de Graaff generator? Fill in each of the boxes the name of the part shown. A device that... and... at high voltage on its dome. dome 2. You

### Insulators Non-metals are very good insulators; their electrons are very tightly bonded and cannot move.

SESSION 11: ELECTRIC CIRCUITS Key Concepts Resistance and Ohm s laws Ohmic and non-ohmic conductors Series and parallel connection Energy in an electric circuit X-planation 1. CONDUCTORS AND INSULATORS

### Electric charge is conserved the arithmetic sum of the total charge cannot change in any interaction.

Electrostatics Electric charge is conserved the arithmetic sum of the total charge cannot change in any interaction. Electric Charge in the Atom Atom: Nucleus (small, massive, positive charge) Electron

### Circuits-Ohm's Law. 1. Which graph best represents the relationship between the electrical power and the current in a resistor that obeys Ohm s Law?

1. Which graph best represents the relationship between the electrical power and the current in a resistor that obeys Ohm s Law? 2. A potential drop of 50 volts is measured across a 250- ohm resistor.

### Electric Currents and Circuits

Nicholas J. Giordano www.cengage.com/physics/giordano Chapter 19 Electric Currents and Circuits Marilyn Akins, PhD Broome Community College Electric Circuits The motion of charges leads to the idea of

### SIMPLE D.C. CIRCUITS AND MEASUREMENTS Background

SIMPLE D.C. CICUITS AND MEASUEMENTSBackground This unit will discuss simple D.C. (direct current current in only one direction) circuits: The elements in them, the simple arrangements of these elements,

Science Olympiad Circuit Lab Key Concepts Circuit Lab Overview Circuit Elements & Tools Basic Relationships (I, V, R, P) Resistor Network Configurations (Series & Parallel) Kirchhoff s Laws Examples Glossary

### Electric Current. Chapter 17. Electric Current, cont QUICK QUIZ Current and Resistance. Sections: 1, 3, 4, 6, 7, 9

Electric Current Chapter 17 Current and Resistance Sections: 1, 3, 4, 6, 7, 9 Whenever electric charges of like signs move, an electric current is said to exist The current is the rate at which the charge

### Section 1 Electric Charge and Force

CHAPTER OUTLINE Section 1 Electric Charge and Force Key Idea questions > What are the different kinds of electric charge? > How do materials become charged when rubbed together? > What force is responsible

### Electric Current & DC Circuits

Electric Current & DC Circuits Circuits Click on the topic to go to that section Conductors Resistivity and Resistance Circuit Diagrams Measurement EMF & Terminal Voltage Kirchhoff's Rules Capacitors*

### Electric Charge. Electric Charge ( q ) unbalanced charges positive and negative charges. n Units Coulombs (C)

Electric Charge Electric Charge ( q ) unbalanced charges positive and negative charges n Units Coulombs (C) Electric Charge How do objects become charged? Types of materials Conductors materials in which

### Electromagnetism Checklist

Electromagnetism Checklist Elementary Charge and Conservation of Charge 4.1.1A Convert from elementary charge to charge in coulombs What is the charge in coulombs on an object with an elementary charge

### STUDY GUIDE CHAPTER 5 ELECTRICITY AND MAGNETISM 1) ASSOCIATE ELEMENTARY PARTICLES WITH THEIR ELECTRICAL CHARGE

Name Date STUDY GUIDE CHAPTER 5 ELECTRICITY AND MAGNETISM 1) ASSOCIATE ELEMENTARY PARTICLES WITH THEIR ELECTRICAL CHARGE Scientists now know that an atom is composed of even smaller particles of matter:

### PhysicsAndMathsTutor.com

Electricity May 02 1. The graphs show the variation with potential difference V of the current I for three circuit elements. PhysicsAndMathsTutor.com When the four lamps are connected as shown in diagram

### Current Electricity.notebook. December 17, 2012

1 Circuit Diagrams and Assembly 1. Draw a circuit diagram containing a battery, a single throw switch, and a light. 2. Once the diagram has been checked by your teacher, assemble the circuit. Keep the

### Chapter 17. Current and Resistance. Sections: 1, 3, 4, 6, 7, 9

Chapter 17 Current and Resistance Sections: 1, 3, 4, 6, 7, 9 Equations: 2 2 1 e r q q F = k 2 e o r Q k q F E = = I R V = A L R ρ = )] ( 1 [ o o T T + = α ρ ρ V I V t Q P = = R V R I P 2 2 ) ( = = C Q

### Notes on Electricity (Circuits)

A circuit is defined to be a collection of energy-givers (batteries) and energy-takers (resistors, light bulbs, radios, etc.) that form a closed path (or complete path) through which electrical current

### Unit 6 Current Electricity and Circuits

Unit 6 Current Electricity and Circuits 2 Types of Electricity Electricity that in motion. Electricity that in motion. Occurs whenever an moves through a. 2 Types of Current Electricity Electricity that

CHAPTER 12 ELECTRICITY Electricity is a general term that encompasses a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena such

### LABORATORY 4 ELECTRIC CIRCUITS I. Objectives

LABORATORY 4 ELECTRIC CIRCUITS I Objectives to be able to discuss potential difference and current in a circuit in terms of electric field, work per unit charge and motion of charges to understand that

### What does it mean for an object to be charged? What are charges? What is an atom?

What does it mean for an object to be charged? What are charges? What is an atom? What are the components of an atom? Define the following: Electric Conductor Electric Insulator Define the following: Electric

### Look over Chapter 26 sections 1-7 Examples 3, 7. Look over Chapter 18 sections 1-5, 8 over examples 1, 2, 5, 8, 9,

Look over Chapter 26 sections 1-7 Examples 3, 7 Look over Chapter 18 sections 1-5, 8 over examples 1, 2, 5, 8, 9, 1)How to find a current in a wire. 2)What the Current Density and Draft Speed are. 3)What

### Direct Current (DC) Circuits

Direct Current (DC) Circuits NOTE: There are short answer analysis questions in the Participation section the informal lab report. emember to include these answers in your lab notebook as they will be

### Electricity. Prepared by Juan Blázquez, Alissa Gildemann. Electric charge is a property of all objects. It is responsible for electrical phenomena.

Unit 11 Electricity 1. Electric charge Electric charge is a property of all objects. It is responsible for electrical phenomena. Electrical phenomena are caused by the forces of attraction and repulsion.

### Dynamic Electricity. All you need to be an inventor is a good imagination and a pile of junk. -Thomas Edison

Dynamic Electricity All you need to be an inventor is a good imagination and a pile of junk. -Thomas Edison Review Everything is made of atoms which contain POSITIVE particles called PROTONS and NEGATIVE

### Direct Current Circuits. February 18, 2014 Physics for Scientists & Engineers 2, Chapter 26 1

Direct Current Circuits February 18, 2014 Physics for Scientists & Engineers 2, Chapter 26 1 Kirchhoff s Junction Rule! The sum of the currents entering a junction must equal the sum of the currents leaving

### What is electricity? Charges that could be either positive or negative and that they could be transferred from one object to another.

Electricity What is electricity? Charges that could be either positive or negative and that they could be transferred from one object to another. What is electrical charge Protons carry positive charges

### AP Physics C - E & M

Slide 1 / 27 Slide 2 / 27 AP Physics C - E & M Current, Resistance & Electromotive Force 2015-12-05 www.njctl.org Slide 3 / 27 Electric Current Electric Current is defined as the movement of charge from

### Chapter 16. Current and Drift Speed. Electric Current, cont. Current and Drift Speed, cont. Current and Drift Speed, final

Chapter 6 Current, esistance, and Direct Current Circuits Electric Current Whenever electric charges of like signs move, an electric current is said to exist The current is the rate at which the charge

### Question 3: How is the electric potential difference between the two points defined? State its S.I. unit.

EXERCISE (8 A) Question : Define the term current and state its S.I unit. Solution : Current is defined as the rate of flow of charge. I = Q/t Its S.I. unit is Ampere. Question 2: Define the term electric

### National 5 Physics. Electricity and Energy. Notes

National 5 Physics Electricity and Energy Notes Name. 1 P a g e Key Area Notes, Examples and Questions Page 3 Conservation of energy Page 10 Electrical charge carriers and electric fields and potential

### College Physics B - PHY2054C

Power College - PHY2054C and 09/15/2014 My Office Hours: Tuesday 10:00 AM - Noon 206 Keen Building PHY2054C Power First Mini-Exam this week on Wednesday!! Location: UPL 101, 10:10-11:00 AM Exam on chapters

### Electric Current. Volta

Electric Current Galvani Volta In the late 1700's Luigi Galvani and Alessandro Volta carried out experiements dealing with the contraction of frogs' leg muscles. Volta's work led to the invention of the

CURRENT ELECTRICITY CHAPTER 13 CURRENT ELECTRICITY Qs. Define Charge and Current. CHARGE Definition Flow of electron is known as Charge. It is denoted by Q. Unit Its unit is Coulomb. 1 Coulomb = 10(-6)

### Tactics Box 23.1 Using Kirchhoff's Loop Law

PH203 Chapter 23 solutions Tactics Box 231 Using Kirchhoff's Loop Law Description: Knight/Jones/Field Tactics Box 231 Using Kirchhoff s loop law is illustrated Learning Goal: To practice Tactics Box 231

### Capacitance. A different kind of capacitor: Work must be done to charge a capacitor. Capacitors in circuits. Capacitor connected to a battery

Capacitance The ratio C = Q/V is a conductor s self capacitance Units of capacitance: Coulomb/Volt = Farad A capacitor is made of two conductors with equal but opposite charge Capacitance depends on shape

### LESSON 5: ELECTRICITY II

LESSON 5: ELECTRICITY II The first two points are a review of the previous lesson 1.1.ELECTRIC CHARGE - Electric charge is a property of all objects and is responsible for electrical phenomena. -All matter

### Static Electricity. Electric Field. the net accumulation of electric charges on an object

Static Electricity the net accumulation of electric charges on an object Electric Field force exerted by an e - on anything that has an electric charge opposite charges attract like charges repel Static

### Lecture Outline Chapter 21. Physics, 4 th Edition James S. Walker. Copyright 2010 Pearson Education, Inc.

Lecture Outline Chapter 21 Physics, 4 th Edition James S. Walker Chapter 21 Electric Current and Direct- Current Circuits Units of Chapter 21 Electric Current Resistance and Ohm s Law Energy and Power

### 12/2/2018. Monday 12/17. Electric Charge and Electric Field

Electricity Test Monday 1/17 Electric Charge and Electric Field 1 In nature, atoms are normally found with equal numbers of protons and electrons, so they are electrically neutral. By adding or removing

### Electricity Final Unit Final Assessment

Electricity Final Unit Final Assessment Name k = 1/ (4pe 0 ) = 9.0 10 9 N m 2 C -2 mass of an electron = 9.11 10-31 kg mass of a proton = 1.67 10-27 kg G = 6.67 10-11 N m 2 kg -2 C = 3 x10 8 m/s Show all

### Chapter 3: Electric Current And Direct-Current Circuits

Chapter 3: Electric Current And Direct-Current Circuits 3.1 Electric Conduction 3.1.1 Describe the microscopic model of current Mechanism of Electric Conduction in Metals Before applying electric field

### Electric Currents. Resistors (Chapters 27-28)

Electric Currents. Resistors (Chapters 27-28) Electric current I Resistance R and resistors Relation between current and resistance: Ohm s Law Resistivity ρ Energy dissipated by current. Electric power

### ELECTRICITY. Prepared by: M. S. KumarSwamy, TGT(Maths) Page

ELECTRICITY 1. Name a device that helps to maintain a potential difference across a conductor. Cell or battery 2. Define 1 volt. Express it in terms of SI unit of work and charge calculate the amount of

### Q-2 How many coulombs of charge leave the power supply during each second?

Part I - Circuit Elements in Series In Figure 1 at the right circuit elements #1, #2, #3 (in this case light bulbs) are said to be connected "IN SERIES". That is, they are connected in a series one right

### Closed loop of moving charges (electrons move - flow of negative charges; positive ions move - flow of positive charges. Nucleus not moving)

Unit 2: Electricity and Magnetism Lesson 3: Simple Circuits Electric circuits transfer energy. Electrical energy is converted into light, heat, sound, mechanical work, etc. The byproduct of any circuit

### Science Practice Exam. Chapters 5 and 14

Science Practice Exam Chapters 5 and 14 FORMULAS Science and Technology FORMULAS C: concentration m: quantity of solute v: quantity of solution V: potential difference R: resistance I: electric current

### Part 4: Electricity & Magnetism

Part 4: Electricity & Magnetism Notes: Magnetism Magnetism Magnets: 1.Have a north and south pole 2.Like poles repel; opposite poles attract - The larger the distance between the magnets, the weaker the

### Physics 7B-1 (A/B) Professor Cebra. Winter 2010 Lecture 2. Simple Circuits. Slide 1 of 20

Physics 7B-1 (A/B) Professor Cebra Winter 2010 Lecture 2 Simple Circuits Slide 1 of 20 Conservation of Energy Density In the First lecture, we started with energy conservation. We divided by volume (making

### Ch 17 Problem Set 31. A toaster is rated at 600 W when connected to a 120-V source. What current does the toaster carry, and what is its resistance?

Ch 17 Problem Set 31. A toaster is rated at 600 W when connected to a 120-V source. What current does the toaster carry, and what is its resistance? 33. How many 100-W lightbulbs can you use in a 120-V

### National 5 Physics. Language Wikipedia. Electricity

National 5 Physics Catlin.Fatu@English Language Wikipedia Electricity Throughout the Course, appropriate attention should be given to units, prefixes and scientific notation. tera T 10 12 x 1,000,000,000,000

### 7.1 ANALYSING ELECTRIC FIELDS AND CHARGE FLOW

7.1 ANALYSING ELECTRIC FIELDS AND CHARGE FLOW State the relationship between electron and electric current Where does charge come from? Matter is made up of tiny particles called atoms. At the center of

### What is an Electric Current?

Electric Circuits NTODUCTON: Electrical circuits are part of everyday human life. e.g. Electric toasters, electric kettle, electric stoves All electrical devices need electric current to operate. n this

### 52 VOLTAGE, CURRENT, RESISTANCE, AND POWER

52 VOLTAGE, CURRENT, RESISTANCE, AND POWER 1. What is voltage, and what are its units? 2. What are some other possible terms for voltage? 3. Batteries create a potential difference. The potential/voltage

### TSOKOS LSN 5-1 TO 5-5 TEST REVIEW

IB HYSICS Name: DEIL HYSICS eriod: Date: # Marks: BADDEST CLASS ON CAMUS TSOKOS LSN 5-1 TO 5-5 TEST REIEW 4. This question is about forces on charged particles. (a) (b) A charged particle is situated in

### Chapter 21 Electric Current and Direct- Current Circuits

Chapter 21 Electric Current and Direct- Current Circuits Units of Chapter 21 Electric Current Resistance and Ohm s Law Energy and Power in Electric Circuits Resistors in Series and Parallel Kirchhoff s

### Electricity. Part 1: Static Electricity

Electricity Part 1: Static Electricity Introduction: Atoms Atoms are made up of charged particles. Atoms are made of 3 subatomic particles: Electrons protons, electrons and neutrons. Protons () Charge

### Use these circuit diagrams to answer question 1. A B C

II Circuit Basics Use these circuit diagrams to answer question 1. B C 1a. One of the four voltmeters will read 0. Put a checkmark beside it. b. One of the ammeters is improperly connected. Put a checkmark

### 5. ELECTRIC CURRENTS

5. ELECTRIC CURRENTS TOPIC OUTLINE Section Recommended Time Giancoli Section 5.1 Potential Difference, Current, Resistance 5.2 Electric Circuits 3h 19.1, 19.2 6.2 Electric Field and Force 6.3 Magnetic

### Electric Current & DC Circuits How to Use this File Electric Current & DC Circuits Click on the topic to go to that section Circuits

Slide 1 / 127 Slide 2 / 127 Electric Current & DC Circuits www.njctl.org Slide 3 / 127 How to Use this File Slide 4 / 127 Electric Current & DC Circuits Each topic is composed of brief direct instruction

### 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

### This week. 3/23/2017 Physics 214 Summer

This week Electrical Circuits Series or parallel that s the question. Current, Power and Energy Why does my laptop battery die? Transmission of power to your home Why do we have big transmission towers?

### This week. 6/2/2015 Physics 214 Summer

This week Electrical Circuits Series or parallel that s the question. Current, Power and Energy Why does my laptop battery die? Transmission of power to your home Why do we have big transmission towers?

### Chapter 21 Electric Current and Circuits

Chapter 21 Electric Current and Circuits 1 As an introduction to this chapter you should view the following movie. If you cannot click on the link, then copy it and paste it into your web browser. http://www.ionaphysics.org/movies/vir.mp4

https://www.youtube.com/watch?v=yc2-363miqs SCIENCE 9 UNIT 3 ELECTRICITY Remember: In the last unit we learned that all matter is made up of atoms atoms have subatomic particles called, protons, neutrons

### REVISED HIGHER PHYSICS REVISION BOOKLET ELECTRONS AND ENERGY

REVSED HGHER PHYSCS REVSON BOOKLET ELECTRONS AND ENERGY Kinross High School Monitoring and measuring a.c. Alternating current: Mains supply a.c.; batteries/cells supply d.c. Electrons moving back and forth,

### Notes on Electricity (Circuits)

A circuit is defined to be a collection of energy-givers (active elements) and energy-takers (passive elements) that form a closed path (or complete path) through which electrical current can flow. The

### 3 Electric current, resistance, energy and power

3 3.1 Introduction Having looked at static charges, we will now look at moving charges in the form of electric current. We will examine how current passes through conductors and the nature of resistance

### Electron Theory. Elements of an Atom

Electron Theory Elements of an Atom All matter is composed of molecules which are made up of a combination of atoms. Atoms have a nucleus with electrons orbiting around it. The nucleus is composed of protons

### MITES Middle School Introduction To Engineering Systems

MITES Middle School Introduction To Engineering Systems 2 Expectations for Behavior Be Respectful To teacher, To Peers, To Facilities Follow 1 st Request From Teachers or Peers Golden Rule Treat others

### Chapter 19. Electric Current, Resistance, and DC Circuit Analysis

Chapter 19 Electric Current, Resistance, and DC Circuit Analysis I = dq/dt Current is charge per time SI Units: Coulombs/Second = Amps Direction of Electron Flow _ + Direction of Conventional Current:

### 9. Which of the following is the correct relationship among power, current, and voltage?. a. P = I/V c. P = I x V b. V = P x I d.

Name: Electricity and Magnetism Test Multiple Choice Identify the choice that best completes the statement. 1. Resistance is measured in a unit called the. a. ohm c. ampere b. coulomb d. volt 2. The statement

### Conceptual Physical Science 6 th Edition

Conceptual Physical Science 6 th Edition Chapter 8: STATIC AND CURRENT ELECTRICITY 1 Chapter 8: STATIC AND CURRENT ELECTRICITY Chapter 8: Read: All Homework: Four problems from the following set: 4, 6,

### Chapter 21 Electric Current and Direct- Current Circuits

Chapter 21 Electric Current and Direct- Current Circuits 1 Overview of Chapter 21 Electric Current and Resistance Energy and Power in Electric Circuits Resistors in Series and Parallel Kirchhoff s Rules

### 1 Written and composed by: Prof. Muhammad Ali Malik (M. Phil. Physics), Govt. Degree College, Naushera

CURRENT ELECTRICITY Q # 1. What do you know about electric current? Ans. Electric Current The amount of electric charge that flows through a cross section of a conductor per unit time is known as electric

### CHARGE AND ELECTRIC CURRENT:

ELECTRICITY: CHARGE AND ELECTRIC CURRENT ELECTRIC CHARGE ELECTRIC CURRENT ELECTRIC CIRCUIT DEFINITION AND COMPONENTS EFFECTS OF ELECTRIC CURRENT TYPES OF CIRCUITS ELECTRIC QUANTITIES VOLTAGE CURRENT RESISTANCE

### physics 4/7/2016 Chapter 31 Lecture Chapter 31 Fundamentals of Circuits Chapter 31 Preview a strategic approach THIRD EDITION

Chapter 31 Lecture physics FOR SCIENTISTS AND ENGINEERS a strategic approach THIRD EDITION randall d. knight Chapter 31 Fundamentals of Circuits Chapter Goal: To understand the fundamental physical principles

### (b) State the relation between work, charge and potential difference for an electric circuit.

Question Bank on Ch-Electricity 1. (a) Define the S.I unit of potential difference. (b) State the relation between work, charge and potential difference for an electric circuit. Calculate the potential

### Ohms Law. V = IR V = voltage in volts (aka potential difference) I = Current in amps R = resistance in ohms (Ω)

Ohms Law V = IR V = voltage in volts (aka potential difference) I = Current in amps R = resistance in ohms (Ω) Current How would you define it? Current the movement of electric charge through a medium