A 40-W instrument has a resistance of 90Ω. On what voltage should it be operated...
PHYSICS
JAMB 1993
A 40-W instrument has a resistance of 90Ω. On what voltage should it be operated normally?
- A. 60V
- B. 150V
- C. 225V
- D. 3600V
Correct Answer: A. 60V
Explanation
P = \(\frac{V}{R}\)
V = \(\sqrt{PR}\)
V = \(\sqrt{40 \times 90}\)
= 60V
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