Magnetic Force Introduction Magnetic force on moving charge

Magnetic Force • • Introduction Magnetic force on moving charge Examples Magnetic deflection animation x and o diagrams More examples Magnetic force on current-carrying wire Still more examples

Magnetism and Induction • Magnetism is weird, both for the force involved and its direction. It’s like a correction to electric forces when charges are in motion, and correction terms are always weird. * – Electric affects charges, magnetism affects charges in motion – Electric causes linear accelerations, magnetism causes sideways deflections (RH rule) • Magnetism and Induction are very, very (societally) important! – Motors, generators, loudspeakers, credit cards, hard drives, transformers…. . *Can derive magnetic force from electric force and Einstein’s theory of relativity

Magnetic Force on moving charge •

Right-hand rule • Hand in direction of v • Bend in direction B • Thumb points in direction of F • Alternative right hand rules

Example - Magnetic Force on moving charge •

Example 2 - Magnetic Force on moving charge • F v

Magnetic force video • mp 4 video

X’s and O’s • Simplify diagrams – B field out of or into plane of paper B coming out B going in (+) deflects to right (-) deflects to right

Circular motion in magnetic field •

Circular motion in magnetic field http: //objetoseducacionais 2. mec. gov. br/bitstream/handle/mec/23847/ciclotron. E. swf? sequence=1

Examples – Force on Moving Charge • Problem 11 – Direction of force for (-) charge • Problem 12 – Direction of field for (+) charge

Problem 11 -12 Answers

More examples – Force on Moving Charge •

Magnetic Deflection http: //neutrons. ornl. gov/about

Magnetic Deflection

Force on Current-carrying wire •

Summary – 2 magnetic force laws •

Example 20 -1 •

Example 20 -2 •

Problem 7 •

Magnetron - Microwave ovens •

Magnetron - Details • Magnets top and bottom

Magnetron - History Amazon. com Tuxedo Park : A Wall Street Tycoon and the Secret Palace of Science That Changed the Course of World War II Paperback – May 6, 2003 by Jennet Conant (Author) • The untold story of an eccentric Wall Street tycoon and the circle of scientific geniuses he assembled before World War II to develop the science for radar and the atomic bomb. Together they changed the course of history. • helped defend Britain from the Blitz! • Could now put radar in planes!

Magnetism and Induction Flowchart law change field Current force direct examples Force Law 1 B → qv → F = qv x B RHR 1 charge deflection picture tube Force Law 2 B → i → F = il x B RHR 1 2 wires, motor, loudspeaker RHR 2 electromagnet solenoid Lentz generator transformer Ampere’s Law Faraday Induction B = μoi/2πr d/dt → ← i Φ = B*A → ε = dΦ/dt i = ε/R Magnetic field plus moving charge/current creates force