What is Ohm's Law?

• A. V = IR
• B. F = ma
• C. P = VI
• D. E = mc^2

Answer: (A)

Ohm's Law describes the relationship among voltage, current, and resistance in many conductive materials. It says that voltage equals current times resistance, written as V = I R. This means that for a given resistor, increasing the voltage increases the current proportionally, while the resistance sets how large the current will be. It’s a practical tool for analyzing circuits: if you know voltage and resistance, you can find the current; if you know current and resistance, you can find the voltage; and if you know voltage and current, you can find the resistance. For example, a 5-volt source across a 2-ohm resistor yields a current of 2.5 amperes (I = V/R). The other formulas listed describe different ideas: one is about force and motion, another gives power in a circuit (which can be derived from Ohm’s Law but is not the basic relation), and the last is a famous equation about mass-energy equivalence.