ARRL Technician Practice Exam 2025 – Complete Prep Guide

Question: 1 / 470

If a circuit draws 4 amperes from a 12-volt source, what is the resistance?

2 ohms

3 ohms

To determine the resistance in a circuit, Ohm's Law can be applied. Ohm's Law states that voltage (V) equals the current (I) multiplied by the resistance (R). This relationship can be expressed with the formula:

\[ R = \frac{V}{I} \]

In the given problem, the voltage (V) is 12 volts and the current (I) is 4 amperes. Plugging these values into the formula gives:

\[ R = \frac{12 \text{ volts}}{4 \text{ amperes}} \]

Carrying out the division results in:

\[ R = 3 \text{ ohms} \]

This calculation indicates that the resistance in the circuit is 3 ohms. Understanding this formula is crucial for anyone working with electrical circuits, as it allows for the calculation of one variable when the other two are known.

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4 ohms

5 ohms

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