IB Physics Induction Practice Questions

Q: A coil of $50$ turns experiences a flux change of $0.02\,\text{Wb}$ in $0.10\,\text{s}$. What is the magnitude of the induced emf?

$10\,\text{V}$. $\varepsilon=N\frac{\Delta\Phi}{\Delta t}=50\times\frac{0.02}{0.10}=10\,\text{V}$.

Question 1

Faraday's law states that the induced emf in a coil is proportional to the:

Accepted Answer

Rate of change of magnetic flux linkage. Faraday's law: $\varepsilon=-N\frac{\Delta\Phi}{\Delta t}$; the emf depends on the rate of change of magnetic flux linkage.

Question 2

Lenz's law states that the direction of an induced current is such that it:

Accepted Answer

Opposes the change producing it. Lenz's law: the induced current opposes the change in flux that produced it, a consequence of energy conservation.

Question 3

A coil of $50$ turns experiences a flux change of $0.02\,	ext{Wb}$ in $0.10\,	ext{s}$. What is the magnitude of the induced emf?

Accepted Answer

$10\,	ext{V}$. $\varepsilon=N\frac{\Delta\Phi}{\Delta t}=50	imes\frac{0.02}{0.10}=10\,	ext{V}$.

Question 4

The law stating that an induced current opposes the change that produces it is _____ law.

Accepted Answer

Lenz's / Lenz / Lenzs. Lenz's law expresses energy conservation in electromagnetic induction, giving the minus sign in Faraday's law.

Question 5

A horizontal ring of area 4.0 cm squared lies perpendicular to a uniform vertical field. It is flipped through 180 degrees in 2.0 s, inducing an average emf of 2.0 microvolts. What is the magnetic flux density?

Accepted Answer

5.0 mT. Flipping reverses the flux, so change in flux = 2 B A; average emf = 2 B A / time; 2.0e-6 = 2 B (4.0e-4)/2.0, giving B = 5.0 x 10^-3 T = 5.0 mT.

Question 6

By Faradays law, the emf induced in a coil equals the rate of change of

Accepted Answer

magnetic flux linkage. The induced emf equals the rate of change of magnetic flux linkage.

Question 7

Faradays law states that the induced emf equals the rate of change of magnetic _____.

Accepted Answer

flux. emf is the rate of change of flux (linkage).

Question 8

Magnetic flux equals the magnetic flux density times the _____ perpendicular to the field.

Accepted Answer

area. Flux = B times area.

Question 9

A conducting ring lies in a uniform magnetic field pointing out of the page, and the field is increasing. What are the induced current direction and the net magnetic force on the ring?

Accepted Answer

Clockwise current; zero net force. By Lenz law the induced current opposes the increase, so it flows clockwise (to make field into the page inside the ring); in a uniform field the net force on the ring is zero.

Question 10

Lenz law states that an induced current flows in a direction that opposes the change in:

Accepted Answer

magnetic flux. The induced current opposes the change in magnetic flux through the loop.

IB Physics: Induction — Practice Questions & Answers

Practice questions with answers

Ready to test yourself?

Practise other IB Physics topics