Four steps, every calculation: write the given values with units, pick the formula that matches the question, carry the units through, and ask whether the answer is reasonable.
The arithmetic is rarely what goes wrong. The setup and the units are, and the fourth step catches what the first three miss.
120 volts across 60 ohms. Given: V = 120 V, R = 60 ohms. The question asks for current, so the formula is I = V / R. That gives 120 / 60 = 2, and the unit that falls out is amperes. Two amps on a 120 volt circuit is a sensible number -- and noticing that is the fourth step doing its job.
Check yourself: You calculate 120 V across 60 ohms. What is the answer and its unit?
Answer: 2 A. The answer unit is amperes.
I = V / R matches the question, so 120 / 60 = 2, and dividing volts by ohms gives amperes. The unit is part of the answer, not decoration on it.
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Written for Texas apprentices as free study material. The Texas apprentice licence is an application, not an exam (Occupations Code 1305.161), and nothing here counts as apprenticeship hours or continuing-education credit. VoltMark is not affiliated with, endorsed by, or sponsored by NFPA, PSI, TDLR, or any state or local licensing authority. Always follow your employer's safety programme and your supervising electrician.
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