alleryStart learning →An automobile headlight passes 2.50 A when 12.0 V is applied to it. What is its resistance?
A0.208 ohm
B4.80 ohm
C9.60 ohm
D30.0 ohm
Answer & Solution
Correct answer: B. 4.80 ohm
1. Ohm's law in the form I = V / R rearranges to R = V / I.
2. Substitute the given values: R = 12.0 V / 2.50 A.
3. That gives R = 4.80 ohm.
4. 0.208 ohm is the reciprocal, from dividing current by voltage.
5. 30.0 ohm comes from multiplying the two numbers, which yields power in watts rather than resistance.
_Source: OpenStax College Physics (CC BY 4.0), Ch 20 "Electric Current, Resistance, and Ohm's Law", section Resistance and Simple Circuits_
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