alleryA Wheatstone bridge is balanced with arms P = 10 Ω, Q = 20 Ω and R = 15 Ω. The unknown resistance S is:
A25 Ω
B7.5 Ω
C30 Ω
D300 Ω
Answer & Solution
Correct answer: C. 30 Ω
At balance P/Q = R/S, so S = R·Q/P = 15×20/10 = 30 Ω.
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