High School

A light bulb uses 12 watts of power when placed across a 12-v battery. Its resistance is ____ ohms.

A. 1
B. 6
C. 12
D. 24

Answer :

Final answer:

The resistance of a light bulb that uses 12 watts of power with a 12-volt battery is 12 ohms, calculated using Ohm's law and the power formula.

Explanation:

To determine the resistance of a light bulb that uses 12 watts of power when placed across a 12-volt battery, you can use Ohm's law, which relates voltage (V), current (I), and resistance (R) in the formula V = IR. First, we need to find the current using the power formula P = VI, which can be rearranged to I = P/V. Substituting the given values, we get I = 12W / 12V = 1A. With the current known, we return to Ohm's law to find resistance as R = V/I = 12V / 1A = 12 ohms.

Therefore, the resistance of the light bulb is 12 ohms.