Which statement best describes the movement of electrical current when a capacitor is used in a circuit?

A. The discharge of a capacitor changes the direction of the current

B. Capacitors prevent current from moving through a circuit

C. Electrical current decreases the storage capacity within the capacitor

D. Electrical current from a capacitor minimizes magnetic fields

Answer: B.

Capacitors prevent current from moving through a circuit

Explanation:

If a direct voltage is applied on the capacitor, no conduction current flows through the capacitor if its insulating medium is perfect insulator. This is due to the fact that there are no free charge carriers in such medium. Basically the real insulator contains very few charge carriers and therefore a very small leakage current passes in the capacitor depending on the conductivity of the insulator.

If an alternating voltage is applied on the capacitor, a displacement current passes through the capacitor irrespective of the insulating medium. This current is termed also the capacitive current. It flows because of changing electric displacement with time.