Question 1

A 1.0 m long metal rod moves at 3.0 m/s perpendicular to Earth's magnetic field ($$B_{	ext{Earth}} = 5 	imes 10$$^{-5}$$\ 	ext{T}). $$What is the magnitude of the motional emf induced across the ends of the rod?

Accepted Answer

$$150\ \mu	ext{V}$$

Question 2

Which of the following best describes why induced electric fields from changing magnetic flux are non-conservative?

Accepted Answer

They form closed loops where $$\oint \vec{E} \cdot d\vec{l} 
eq 0$$

Question 3

A metal plate swings through a magnetic field and slows down due to magnetic damping. What is the primary cause of this damping?

Accepted Answer

Eddy currents induced in the plate create a magnetic force opposing the motion

Question 4

Which real-world application relies on eddy currents to function?

Accepted Answer

Electromagnetic braking in roller coasters

Question 5

For two coils with $$N_1$$ and $$N_2$$ turns, the mutual inductance $$M is $$defined as:

Accepted Answer

$$M = \frac{N_2$ \Phi_{21}}{I_1$}$$

Question 6

Which equation correctly expresses the emf $$\$$epsilon_1$$ induced in coil 1 due to a changing current in coil 2?

Accepted Answer

$$\$$epsilon_1$$ = -M \frac{dI_2$}{dt}$$

Question 7

A slotted metal bob swings through a magnetic field. Compared to a solid metal bob, the slotted bob experiences:

Accepted Answer

Less magnetic damping because eddy currents form small loops that cancel

Question 8

Which of the following statements about self-inductance is correct?

Accepted Answer

A changing current in a coil induces an emf in itself that opposes the change

Question 9

The voltage across an inductor is given by:

Accepted Answer

$$V = L \frac{dI}{dt}$$

Question 10

Which of the following is a correct analogy between Newton's law and self-inductance in a circuit?

Accepted Answer

Force $$F is $$analogous to potential difference $$V$$

Question 11

A metal detector works by:

Accepted Answer

Detecting eddy currents induced in metal objects by a changing magnetic field

Question 12

Which of the following is true about mutual inductance $$M_{12}$$ and $$M_{21}$$ for two coils?

Accepted Answer

$$M_{12} = M_{21}$$

Question 13

Which of the following best explains why electromagnetic braking is used in high-speed trains?

Accepted Answer

It provides non-contact braking by inducing eddy currents that oppose motion

Question 14

If the current in a coil is increasing, what is the direction of the induced emf due to self-inductance?

Accepted Answer

It opposes the increase in current (Lenz's law)

Question 15

Which formula gives the emf induced in a loop by a changing magnetic flux?

Accepted Answer

$$\mathcal{E} = -\frac{d\Phi_B}{dt}$$

Question 16

A phone is charged wirelessly using inductive charging. Which principle is primarily responsible for this technology?

Accepted Answer

Mutual inductance between two coils

Question 17

Which of the following is NOT a typical application of eddy currents?

Accepted Answer

Generating static electricity

Question 18

If a conducting rod moves through a magnetic field but is not part of a closed circuit, what happens?

Accepted Answer

A separation of charge occurs, creating a potential difference across the rod

Question 19

Which of the following best describes the units of mutual inductance?

Accepted Answer

Henry ($$	ext{H} = 	ext{V} \cdot 	ext{s} / 	ext{A})$$

Question 20

A current in coil 1 is changing at a rate of $$2\ 	ext{A/s}$$, and the mutual inductance between coil 1 and coil 2 is $$0.5\ 	ext{H}. $$What is the magnitude of the emf induced in coil 2?

Accepted Answer

$$1.0\ 	ext{V}$$

LEC 6: Electromagnetic Induction & Inductance: Study Notes for Physics 2101A

Study Guide - Practice Questions

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