Ham Radio General Class Practice Test 2026 – Complete Exam Prep

To determine the wattage of a light bulb powered by a 12-volt direct current (DC) source, you can use the formula for electrical power, which is calculated as the product of voltage and current. The formula is:

Power (in watts) = Voltage (in volts) × Current (in amperes)

In this scenario, the voltage is 12 volts and the current drawn by the light bulb is 0.2 amperes. Plugging in these values into the formula:

Power = 12 volts × 0.2 amperes

Power = 2.4 watts

This calculation shows that the light bulb is using 2.4 watts of electrical power, which makes this the correct answer.

Contextually, the other options do not align with the correct calculation. For example, if you were to consider 24 watts, that would require a current of 2 amperes at 12 volts, which is not the case here. Similarly, the other wattage options represent different combinations of voltage and current that do not match the specifications given in the question. Thus, understanding the basic power calculation reinforces the correctness of the result itself.