Final answer:
A current can be induced in a closed circuit by moving it through a magnetic field based on Faraday's law of electromagnetic induction.
Step-by-step explanation:
A current can be induced in a closed circuit without the use of a battery or an electrical power supply by moving the circuit through a magnetic field. When a conductor, such as a wire, moves through a magnetic field, a change in magnetic flux occurs, which induces a current in the wire according to Faraday's law of electromagnetic induction. This phenomenon is the basis for the operation of generators and many other electrical devices.
Learn more about Electromagnetic Induction