2nd Right Hand Rule

• Fingers still go in direction of the magnetic field

• Thumb goes in the direction of the velocity of the particle (current)

What happens if you wrap the wire around a cylinder?

Electromagnetic InductionOersted discover that electricity produces a magnetic field around the current.

Faraday & Henry discovered that moving a magnet in a coil of wire induces a current.

Faster motion = more currentMore loops = more current

Wire must cut across the field lines

It also works the other way!

Faraday’s Law (Another One of Maxwell’s Equations)

• Induced voltage in a coil is directly proportional to the product of the number of loops, the area of the loops, and the rate at which the magnetic field changes

• V α # of Loops• V α A of loops• V α ΔB/Δt

B A

tε ⊥=

∆

Magnetic Flux, Φ The amount of magnetic field going perpendicularly through

a certain area.

Φ = B┴ A = B A cos θB

t

∆Φ= −∆

Faraday’s Law (Another One of Maxwell’s Equations)

• Induced voltage in a coil is directly proportional to the product of the number of loops, the area of the loops, and the rate at which the magnetic field changes

• V α # of Loops• V α A of loops• V α ΔB/Δt

B A

tε ⊥=

∆

Magnetic Flux, Φ The amount of magnetic field going perpendicularly through

a certain area.

Φ = B┴ A = B A cos θB

t

∆Φ= −∆

Motors & Generators

Generator mechanical energy in, electricity outhttp://www.walter-fendt.de/ph11e/generator_e.htm

Could you hook these together and have them run forever?

No! Law of Conservation of Energy! Energy is lost to heat in process.

Motor electricity in, mechanical energy out http://www.walter-fendt.de/ph11e/electricmotor.htm

Motors & Generators

Generator mechanical energy in, electricity outhttp://www.walter-fendt.de/ph11e/generator_e.htm

Could you hook these together and have them run forever?

No! Law of Conservation of Energy! Energy is lost to heat in process.

Motor electricity in, mechanical energy out http://www.walter-fendt.de/ph11e/electricmotor.htm