Physics Electricity and Magnetism 4

Question 1

Which of Maxwell's equations states that magnetic monopoles do not exist?

Accepted Answer

∇·B = 0

Answer

∇·E = ρ/ε₀

Answer

∇×E = -∂B/∂t

Answer

∇×B = μ₀J

Question 2

A transformer has 200 primary turns and 50 secondary turns. If the primary voltage is 120 V, what is the secondary voltage?

Accepted Answer

30 V

Answer

480 V

Answer

60 V

Answer

240 V

Question 3

The Lorentz force law for a charge q moving with velocity v in fields E and B is:

Accepted Answer

F = q(E + v×B)

Answer

F = qE only

Answer

F = qv×B only

Answer

F = q(E - B)

Question 4

What is the direction of the induced current in a loop when the magnetic flux through it is decreasing?

Accepted Answer

In the direction that increases the flux (opposing the decrease)

Answer

In the direction that decreases the flux further

Answer

Perpendicular to the plane of the loop

Answer

There is no induced current

Question 5

A charge of 3 μC is placed in an electric field of 2,000 N/C. What force does it experience?

Accepted Answer

Both A and B

Answer

0.006 N

Answer

6×10⁻³ N

Answer

6×10⁻⁸ N

Question 6

In Gauss's Law, the total electric flux through a closed surface equals:

Accepted Answer

The enclosed charge divided by ε₀

Answer

The surface area times E

Answer

The enclosed charge times ε₀

Answer

Zero for any closed surface

Question 7

Which of the following materials has the highest electrical conductivity?

Accepted Answer

Copper

Answer

Silicon

Answer

Glass

Answer

Rubber