An electrical device that operates on the principle of magnetism is a ______.

• A. Transformer
• B. Motor
• C. Capacitor
• D. Resistor

Answer: (B)

Electric machines that use magnetic forces to do work are motors. In a motor, current flowing through windings creates magnetic fields that interact with permanent magnets or with other electromagnets. This interaction produces torque, causing the rotor to turn and convert electrical energy into mechanical energy. The other options don’t produce motion: a transformer uses changing magnetic fields to transfer energy between circuits, not to move parts; a capacitor stores energy in an electric field; a resistor converts electrical energy to heat. So the device described is a motor.