Displacement Current — Practice Quiz

Question 1

A parallel-plate capacitor with circular plates of radius R = 5 cm is charged so that E between the plates changes at dE/dt = 10¹⁰ V/m·s. The displacement current through the gap is:

Accepted Answer

0.7 mA

Answer

1.4 mA

Answer

70 mA

Answer

0.07 mA

Question 2

In Ampère–Maxwell law, the displacement current term is necessary because:

Accepted Answer

It explains why B exists even where no charges move

Answer

Real currents are too small

Answer

It corrects errors in Ohm's law

Answer

It only matters at very high frequency

Question 3

A capacitor of 1 μF is connected to a 50 Hz AC source of peak voltage 100 V. The peak displacement current between the plates is:

Accepted Answer

3.14 × 10⁻² A

Answer

3.14 × 10⁻³ A

Answer

0.314 A

Answer

6.28 × 10⁻² A

Question 4

Between the plates of a parallel-plate capacitor being charged, which statement is correct?

Accepted Answer

Only displacement current exists, equal to the conduction current in the wire

Answer

Only conduction current exists

Answer

Both are equal and add

Answer

Neither exists

Question 5

The displacement current produces:

Accepted Answer

A magnetic field identical to that of an equal conduction current

Answer

No magnetic field at all

Answer

A field weaker by factor μ₀

Answer

An electric field only