Even the ancients knew about magnets.

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Russell Johnston
5 years ago
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1 Een the ancients knew about magnets Ho ho, foolish explorers your compasses are useless here! Magnetic Fields hae units of Tesla Magnetic Fields hae a symbol () = 01 Tesla For example: = 01 Tesla 1

2 = 3x10-5 Tesla = 100 Tesla Great Moments in Science n t the was year an 1819 accident! didn t mean to do it Hans Christian Oersted ut, it was ery cool! The Magnetic Field () Circulates Around the Current Like This Produces Magnetism from Electricity Right Hand Rule #1 Use: Direction of Field produced by a current flow Point your right thumb in the direction of the current (or E field) and your fingers will curl in the direction of the magnetic field 2

3 llustrate Magnetic Fields llustrate Magnetic Fields t s a Vector Field Towards You llustrate Magnetic Fields Find the direction of the field at point A created by the electric current flowing out of the page 1 Right 2 Left 3 Up 4 Down 5n the page 6 Out of the page Up Left Right Down A Field Towards You Field Away from You Q Find the direction of the field at point A created by the electric current flowing out of the page Current () 1 Right 2 Left 3 Up 4 Down 5n the page 6 Out of the page A 3

Ampere s Law The Field a distance R away from a straight current ()

r μ 0 = R 2π R Example: At one instant a 2 ion moing with a elocity of

moing in a magnetic field may experience a magnetic force 1 Object must

stationary charge is zero 3 The magnetic force on a charge that is moing

4 Ampere s Law The Field a distance R away from a straight current () carrying conductor r μ0 = 2π Where: R μ o = 4πx10-7 T m/a Example Picture r μ 0 = R 2π R Example: At one instant a 2 ion moing with a elocity of 1000m/s is 2m from a current carrying wire of 50 A What is the -field at the location of the ion? 50A 2m μ 0 ( = amps ) 7 4π = = T 2π R 2π ( 2 m) An object moing in a magnetic field may experience a magnetic force 1 Object must hae a charge (electron, proton, -1 ion) 2 The magnetic force on a stationary charge is zero 3 The magnetic force on a charge that is moing in the direction of the magnetic field is also zero 4 The magnetic force is largest on a charge that is moing perpendicular to the magnetic field 4

As an equation, the force on a Charged Particle in a Magnetic Field is F = Q sinθ Where: Q = Charge of the particle V = the elocity of the particle = the magnetic field Follows a Circular Path Why is

5 As an equation, the force on a Charged Particle in a Magnetic Field is F = Q sinθ Where: Q = Charge of the particle V = the elocity of the particle = the magnetic field Follows a Circular Path Why is the equation F = Q sin θ And not F = Q? f the elocity is not at right angles to the field, you must use a ector component that is F = Q sinθ θ elocity Find the direction of the magnetic F acting on an electron moing along the magnetic field lines 1 Up 2 Down 3 nto the page 4 Out of the page 5 F=0 Force out of the board Q x F z Charge Velocity, Field, and The Force Produced, are all at right angles to each other y Right Hand Rule #2: Direction of force on a moing positie charge in a magnetic field Field Arrows Direction of positie charge flow Force The direction of the force on a negatie charge is opposite that for a positie charge 5

6 Find the direction of the magnetic F acting on an electron moing along the magnetic field lines 1 Up 2 Down 3 nto the page 4 Out of the page 5 F=0 Example: At one instant a 2 ion moing with a elocity of m/s is 20 m from a current carrying wire of 500 A (A) What is the charge of a 2 ion? () What is the force on the ion from the wire? 500A Atoms hae equal numbers of protons and electrons A 2 ion has lost two 20m electrons (or has two more protons than electrons) Q = 2( C) Example: At one instant a 2 ion moing with a elocity of m/s is 20m from a current carrying wire of 500A (A) What is the -field at the location of the ion? () What is the force on the ion from the wire? 50A (remember = 500x10-7 T from preious example) 2m r r r F = Q 19 7 ( 10 C/ )( 1000)( ) = 216 e = N Example: At one instant a 2 ion moing with a elocity of 1000m/s is 2m from a current carrying wire of 50 A (A) What is the -field at the location of the ion? () What is the force on the ion from the wire? 50A (remember = 50x10-7 T from preious example) 2m r r r F = Q 19 7 ( 10 C/ )( 1000)( ) = 216 e = N What is the direction of the force? x x x x x x x x x x - Find the direction of the magnetic F acting on an electron moing inside the uniform 1 Up 2 Down 3 nto the page 4 Out of the page 5 Right 6 Left x x x x x Q 6

7 Find the direction of the magnetic F acting on an electron moing inside the uniform Charged Particles Moing n a Magnetic Field 1 Up 2 Down 3 nto the page 4 Out of the page 5 Right 6 Left 7

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Magnetism has been observed since roughly 800 B.C. Certain rocks on the Greek peninsula of Magnesia were noticed to attract and repel one another.

Magnetism has been observed since roughly 800 B.C. Certain rocks on the Greek peninsula of Magnesia were noticed to attract and repel one another. 1.1 Magnetic ields Magnetism has been obsered since roughly 800.C. Certain rocks on the Greek peninsula of Magnesia were noticed to attract and repel one another. Hence the word: Magnetism. o just like