In Ohm's Law, what quantity does E represent in the formula E = I x R?

In Ohm's Law, what quantity does E represent in the formula E = I x R?

• A. Electromotive force (voltage)
• B. Current
• C. Resistance
• D. Power

Answer: (A)

The quantity E represents electromotive force, i.e., voltage. In Ohm’s Law, E (the driving potential) is the energy per unit charge provided to push charges around the circuit. The relationship E = I × R expresses that the driving voltage equals the current through the circuit times the resistance it encounters—the same idea as the voltage drop across a resistor being IR. This is why the voltage you measure driving current through a resistor is proportional to both how hard the source pushes (emf) and how much the resistor resists the flow (R). It’s not the current (I) or the resistance (R) themselves, and not the power (P), which would be related by P = VI or P = I^2R.

The quantity E represents electromotive force, i.e., voltage. In Ohm’s Law, E (the driving potential) is the energy per unit charge provided to push charges around the circuit. The relationship E = I × R expresses that the driving voltage equals the current through the circuit times the resistance it encounters—the same idea as the voltage drop across a resistor being IR. This is why the voltage you measure driving current through a resistor is proportional to both how hard the source pushes (emf) and how much the resistor resists the flow (R). It’s not the current (I) or the resistance (R) themselves, and not the power (P), which would be related by P = VI or P = I^2R.