What formula is used to calculate voltage in a circuit?

The correct approach to calculate voltage in a circuit is derived from Ohm's Law, which states that voltage (E) is equal to current (I) multiplied by resistance (R). This relationship is foundational in understanding electrical circuits.

The formula can be mathematically expressed as:

E = I × R

In this context, voltage represents the electrical potential difference, current is the flow of electric charge, and resistance is a measure of how much the circuit opposes that flow. Understanding this relationship enables ham radio operators and other technicians to troubleshoot and design circuits effectively.

The other options do not reflect the correct relationship as defined by Ohm’s Law; they involve incorrect operations such as division, addition, or subtraction rather than multiplication, making them invalid for calculating voltage in a circuit.