The Magnetic Field 3

Question 1

Induction

Answer 1

E fields generated by a varying magnetic flux

Question 2

Mechanical energy is converted into what for motional emf?

Answer 2

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

Question 3

induce

Answer 3

gives rise to

Question 4

What gets induced? (order of induction)

Answer 4

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

Question 5

Lenz’s Law

Answer 5

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

Question 6

L

Answer 6

Inductance, constant of proportionality

Question 7

Steady state

Answer 7

no change in flux

Question 8

Determining direction of self-induced emf

Answer 8

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

Question 9

How an inductor works

Answer 9

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

Question 10

Magnetic flux is proportional to what?

Answer 10

both magnetic field and current

Question 11

Inductance is similar to what?

Answer 11

Capacitance

Question 12

Like capacitance, inductance is dependent upon…

Answer 12

geometric factors only

Question 13

Another name for self-induced emf

Answer 13

back emf

Question 14

Difference between RC and RL circuits

Answer 14

RC circuits - increase/decrease in charge

RL circuits - increase/decrease in current

Question 15

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

Answer 15

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.

Question 16

Does the circuit itself have an inductance?

Answer 16

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

Question 17

What makes current response slow?

Answer 17

Inductors

Question 18

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

Answer 18

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

Question 19

Energy in a magnetic field like…

Answer 19

Energy in a capacitor

Question 20

Oscillations in an LC circuit mimmick what?

Answer 20

Simple harmonic motion

Question 21

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

Answer 21

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

Question 22

Angular velocity units

Answer 22

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