ARRL Technician Practice Exam

How many amperes are flowing in a circuit when the applied voltage is 12 volts DC and the load is 120 watts?

1. 8 amperes

2. 10 amperes

3. 12 amperes

4. 15 amperes

The correct answer is: 10 amperes

To find the current flowing in the circuit when the applied voltage is 12 volts DC and the load is 120 watts, you can use the formula derived from Ohm's Law and the power formula: Power (P) is equal to Voltage (V) times Current (I), which can be expressed as: \[ P = V \times I \] To find the current (I), you can rearrange this formula to: \[ I = \frac{P}{V} \] Substituting the values from the question: \[ I = \frac{120 \text{ watts}}{12 \text{ volts}} \] Calculating this gives: \[ I = 10 \text{ amperes} \] This calculation shows that when a load of 120 watts is connected across a circuit with a voltage of 12 volts, the resulting current flowing through the circuit is indeed 10 amperes. This understanding of the relationship between power, voltage, and current is crucial for working with electrical circuits, especially when dealing with different load configurations.