Physics Electricity and Magnetism 3

Question 1

A long straight wire carries 5 A of current. What is the magnetic field at a distance of 0.1 m from the wire? (μ₀ = 4π×10⁻⁷ T·m/A)

Accepted Answer

1×10⁻⁵ T

Answer

10⁻⁶ T

Answer

2π×10⁻⁵ T

Answer

10⁻⁷ T

Question 2

Which of the following best describes a diamagnetic material?

Accepted Answer

Weakly repelled by magnetic fields

Answer

Strongly attracted to magnetic fields

Answer

Weakly attracted to magnetic fields

Answer

Retains magnetization after field removal

Question 3

An EMF of 20 V is induced in a coil when the current changes at a rate of 4 A/s. What is the self-inductance of the coil?

Accepted Answer

5 H

Answer

80 H

Answer

0.2 H

Answer

16 H

Question 4

In a series RLC circuit at resonance, the impedance is:

Accepted Answer

Equal to R only

Answer

Zero

Answer

Equal to X_L - X_C

Answer

Maximum

Question 5

A proton moves east in a uniform magnetic field directed north. In which direction is the magnetic force on the proton?

Accepted Answer

Upward

Answer

Downward

Answer

West

Answer

South

Question 6

The electric potential at a distance r from a point charge Q is given by:

Accepted Answer

kQ/r

Answer

kQ/r²

Answer

kQ²/r

Answer

kQ·r

Question 7

Three resistors of 6 Ω each are connected in parallel. What is the equivalent resistance?

Accepted Answer

2 Ω

Answer

18 Ω

Answer

6 Ω

Answer

3 Ω