The variable letter 'E' in Ohm's Law stands for ?, and is measured in ?.

The variable letter 'E' in Ohm's Law stands for ?, and is measured in ?.

• A. efficacy force / amps
• B. electromotive force / ohms
• C. electromotive force / volts
• D. efficacy force / watts

Answer: (C)

E represents electromotive force—the driving electrical potential that pushes charges through a circuit. In Ohm’s Law form, E is the voltage provided by a source, and its unit is volts. You can think of a battery supplying an emf of, say, 1.5 volts; if a resistor of 3 ohms is connected, the current would be I = E/R = 1.5/3 = 0.5 A. Emf is the source of the potential difference; in an ideal source it matches the voltage across the circuit, though real sources have internal resistance that makes terminal voltage differ from the emf. The other options mix in wrong terms (efficacy force isn’t a electrical quantity) or wrong units (ohms measure resistance, watts measure power, amps measure current). So electromotive force, measured in volts, is the correct pairing.

E represents electromotive force—the driving electrical potential that pushes charges through a circuit. In Ohm’s Law form, E is the voltage provided by a source, and its unit is volts. You can think of a battery supplying an emf of, say, 1.5 volts; if a resistor of 3 ohms is connected, the current would be I = E/R = 1.5/3 = 0.5 A. Emf is the source of the potential difference; in an ideal source it matches the voltage across the circuit, though real sources have internal resistance that makes terminal voltage differ from the emf. The other options mix in wrong terms (efficacy force isn’t a electrical quantity) or wrong units (ohms measure resistance, watts measure power, amps measure current). So electromotive force, measured in volts, is the correct pairing.