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
= 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
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 () 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 10 50 = = 50 10 7 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 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
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 10000 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(16 10 19 C) Example: At one instant a 2 ion moing with a elocity of 10000 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)( 50 10 ) = 216 e = 16 10 21 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)( 50 10 ) = 216 e = 16 10 21 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
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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