A device for storing electrical energy.

A device for storing electrical energy.

• A. Conductor
• B. Condenser
• C. Coil
• D. Circuit protector

Answer: (B)

The main idea is recognizing a device that stores electrical energy in an electric field between two conductors separated by a dielectric. This is the condenser, the historical term for what we now call a capacitor. When you charge it, energy is stored as electrostatic energy, with the amount given by W = 1/2 C V^2. That stored energy can be released later as current flows. The other options aren’t about storing energy in that way: a conductor is just a path for current and doesn’t hold charge on its own; a coil (inductor) stores energy in a magnetic field, not primarily as a portable energy reservoir; a circuit protector’s job is to interrupt or limit current to protect the circuit, not to store energy. So the device described is the condenser.

The main idea is recognizing a device that stores electrical energy in an electric field between two conductors separated by a dielectric. This is the condenser, the historical term for what we now call a capacitor. When you charge it, energy is stored as electrostatic energy, with the amount given by W = 1/2 C V^2. That stored energy can be released later as current flows. The other options aren’t about storing energy in that way: a conductor is just a path for current and doesn’t hold charge on its own; a coil (inductor) stores energy in a magnetic field, not primarily as a portable energy reservoir; a circuit protector’s job is to interrupt or limit current to protect the circuit, not to store energy. So the device described is the condenser.