What term is the voltage that a battery or other source will supply to drive charge around a complete circuit?

What term is the voltage that a battery or other source will supply to drive charge around a complete circuit?

• A. Electromotive force
• B. Potential difference
• C. Current
• D. Electric field

Answer: (A)

The idea being tested is electromotive force. It’s the energy per unit charge that a source such as a battery can supply to push charges round the entire circuit. It represents the maximum voltage the source can provide to drive current when no current is drawn. In a real battery, internal resistance means the actual voltage delivered under load is a bit less, with terminal voltage equal to emf minus the drop from I times internal resistance. By contrast, potential difference is simply the voltage between two points in the circuit, current is the rate of charge flow, and the electric field is the force per unit charge in space.

The idea being tested is electromotive force. It’s the energy per unit charge that a source such as a battery can supply to push charges round the entire circuit. It represents the maximum voltage the source can provide to drive current when no current is drawn. In a real battery, internal resistance means the actual voltage delivered under load is a bit less, with terminal voltage equal to emf minus the drop from I times internal resistance.

By contrast, potential difference is simply the voltage between two points in the circuit, current is the rate of charge flow, and the electric field is the force per unit charge in space.