Which law states that voltage equals current times resistance, commonly summarized as 'one volt to push one amp through one ohm'?

• A. Lenz's Law
• B. Watt's Law
• C. Kirchhoff's Law
• D. Ohm's Law

Answer: (D)

Voltage equals current times resistance describes how electric potential difference relates to how much current flows through a conductor with a given resistance. This relationship is Ohm's Law, written as V = I × R. The phrase “one volt to push one amp through one ohm” is a handy memory aid: if R is 1 ohm and I is 1 amp, then V equals 1 volt. This law lets you predict how changing voltage, current, or resistance will affect the others, which is why it’s the go-to tool for analyzing many circuits, especially DC circuits with components whose resistance stays roughly constant.

Ohm's Law applies best to ohmic, linear components where resistance doesn't change much with current or voltage. For devices whose resistance varies with temperature or voltage (non-ohmic components), the simple V = IR relationship becomes an approximation and you may need a more detailed model. Other laws in electronics describe different ideas—induced currents and magnetic effects, or how power relates to voltage and current—not this direct V = IR relationship.