Question

A battery is a source of​

Answer 1

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EMF - Electromotive Force.

Answer 2

A battery is a device consisting of one or more electrochemical cells with external connections for powering electrical devices such as flashlights, mobile phones, and electric cars. When a battery is supplying electric power, its positive terminal is the cathode and its negative terminal is the anode.

so, the answer is electromotive force.