Which statement is true about capacitors?

• A. Capacitors store energy in a magnetic field
• B. Capacitors oppose a change in voltage
• C. Capacitors dissipate power as heat
• D. Capacitors require a magnetic core to operate

Answer: (B)

Capacitors resist rapid voltage changes because they store energy in an electric field between their plates and respond to voltage changes with a current proportional to the rate of change of voltage (i = C dv/dt). When the voltage across a capacitor tries to swing quickly, charge must flow to build or remove that electric field, so the capacitor automatically acts to oppose that change by supplying or absorbing charge. That’s why this statement is the true reflection of how capacitors behave.

Capacitors store energy in the electric field, not in a magnetic field—that role belongs to inductors. An ideal capacitor does not dissipate power as heat; the energy during charging or discharging goes into or out of the electric field, though real capacitors have losses due to parasitics like equivalent series resistance. And capacitors don’t require a magnetic core to operate; they function based on electric fields between plates.

So, the best description is that capacitors oppose a change in voltage due to their fundamental i = C dv/dt relationship and energy storage in the electric field.