In Ohm's Law, which expression correctly relates voltage, current, and resistance?

In Ohm's Law, which expression correctly relates voltage, current, and resistance?

• A. I = E x R
• B. E = I x R
• C. E = I / R
• D. E = R / I

Answer: (B)

Voltage is the product of current and resistance. This reflects how much voltage is needed to drive a particular current through a component with a given resistance: if you double the voltage while resistance stays the same, the current doubles; if you increase resistance at the same voltage, the current drops. With E representing voltage, I representing current, and R representing resistance, the direct expression is E = I × R. You can rearrange it to I = E / R, but the form E = I × R directly shows how voltage relates to both current and resistance. The other forms would not give voltage with the correct units or behavior: for example, E = I / R would give a quantity with units of current per resistance, not volts; E = R / I would give resistance per current, also not volts; and I = E × R would imply current equals voltage times resistance, which mismatches the units and the observed relationship.

Voltage is the product of current and resistance. This reflects how much voltage is needed to drive a particular current through a component with a given resistance: if you double the voltage while resistance stays the same, the current doubles; if you increase resistance at the same voltage, the current drops. With E representing voltage, I representing current, and R representing resistance, the direct expression is E = I × R. You can rearrange it to I = E / R, but the form E = I × R directly shows how voltage relates to both current and resistance. The other forms would not give voltage with the correct units or behavior: for example, E = I / R would give a quantity with units of current per resistance, not volts; E = R / I would give resistance per current, also not volts; and I = E × R would imply current equals voltage times resistance, which mismatches the units and the observed relationship.