Induction

E fields generated by a varying magnetic flux

Mechanical energy is converted into what for motional emf?

It is converted into power burned over the resistor (electrical energy) - energy is conserved.

induce

gives rise to

What gets induced? (order of induction)

E field induces emf which induces current which induces magnetic field.

Lenz’s Law

The negative sign in Faraday’s law indicates that the polarity of the induced emf is such that the magnetic field due to the induced current opposes the change in magnetic flux through the area enclosed by the current loop

L

Inductance, constant of proportionality

Steady state

no change in flux

Determining direction of self-induced emf

The polarity of the self-induced emf opposes the change in magnetic flux.

How an inductor works

Current I passing through an inductor with N turns produces a flux through the interior of the inductor

Magnetic flux is proportional to what?

both magnetic field and current

Inductance is similar to what?

Capacitance

Like capacitance, inductance is dependent upon…

geometric factors only

Another name for self-induced emf

back emf

Difference between RC and RL circuits

RC circuits - increase/decrease in charge

RL circuits - increase/decrease in current

When the switch is closed to a in a RL circuit, what does the inductor do?

It initially opposes the change in current with a back emf. At t=0s, it behaves like a broken wire. At t=many seconds, it behaves like a connecting wire.

Does the circuit itself have an inductance?

Yes, but it is assumed that the inductance of the inductor is much larger than that of the circuit.

What makes current response slow?

Inductors

Current growth: I(0), Vr(0), VL(0)

I(0)=0, Vr(0)=-IR=0, VL(0)= - epsilon

Energy in a magnetic field like…

Energy in a capacitor

Oscillations in an LC circuit mimmick what?

Simple harmonic motion

In an LC circuit, the energy stored in a capacitor’s electric field is transferred to

the magnetic field of the inductor (after the energy in the electric field generates a current).

Angular velocity units

1 / s