Which electrical property enables a component to store electricity and retain a charge after disconnection?

• A. Capacitance
• B. Inductance
• C. Resistance
• D. Conductance

Answer: (A)

Capacitance is the property that lets a component store electric charge after the source is disconnected. A capacitor achieves this by having two conductors separated by a dielectric; when voltage is applied, charges accumulate on the plates, creating an electric field. Even after the supply is removed, the charge remains on the plates for a time, so the component can still hold voltage across its terminals until leakage gradually discharges it. The stored charge is related by Q = C × V, and the stored energy is E = 1/2 × C × V^2, so higher capacitance means more charge and energy at the same voltage.

Inductance, on the other hand, stores energy in a magnetic field created by current, not as a stationary electric charge, so it doesn’t keep a charge once the circuit is opened. Resistance describes how much a material opposes current and dissipates energy as heat rather than storing it. Conductance is the ease of current flow (the reciprocal of resistance) and also does not involve storing a charge.