ARRL Technician Practice Exam

What is the voltage across a 2-ohm resistor if a current of 0.5 amperes flows through it?

1. 0.5 volts

2. 1 volt

3. 2 volts

4. 4 volts

The correct answer is: 1 volt

To determine the voltage across a resistor when you know the resistance and the current flowing through it, you can use Ohm's Law, which states that voltage (V) is equal to current (I) multiplied by resistance (R). The formula is given as: \[ V = I \times R \] In this case, the resistance (R) is 2 ohms, and the current (I) is 0.5 amperes. Plugging these values into the formula gives: \[ V = 0.5 \, \text{A} \times 2 \, \Omega \] \[ V = 1 \, \text{volt} \] Thus, the voltage across the 2-ohm resistor when a current of 0.5 amperes flows through it is indeed 1 volt. This calculation effectively demonstrates how Ohm's Law is applied in practical scenarios to find voltage when both current and resistance are known. Understanding this principle is fundamental in electronics and helps in troubleshooting and designing circuits effectively.