ARRL Technician Practice Exam 2025 - Free Technician License Practice Questions and Study Guide

The formula used to calculate voltage in a circuit is derived from Ohm's Law, which states that voltage equals current multiplied by resistance. This can be mathematically expressed as V = I × R, where V represents voltage, I represents current, and R represents resistance.

In this context, when knowing the current flowing through a circuit and the resistance of the circuit components, one can accurately determine the voltage being supplied or dropped across those components. This fundamental principle is essential for understanding how electrical circuits function and is widely used in both theory and practical applications.

The other calculation choices do not align with the established principles of Ohm's Law. For instance, dividing current by resistance would not provide a meaningful measurement for voltage, nor would dividing voltage by current; these operations refer to different relationships within electrical circuits. Thus, multiplying current by resistance correctly reflects the relationship defined by Ohm's Law.