In an ammeter, 5% of the main current passes through the galvanometer. If resistance of the galvanometer is G, the resistance of ammeter will be:
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Question

In an ammeter, 5% of the main current passes through the galvanometer. If resistance of the galvanometer is G, the resistance of ammeter will be:

G1 Physics · Accepted Answer

Let total current be I. Current through galvanometer: I(g) = 5I/100 Current through shunt: I(s) = 95I/100 Since galvanometer and shunt are in parallel: I(s)S = I(g)G (95I/100)S = (5I/100)G S = G/19 Equivalent resistance of ammeter: R(A) = SG/(S + G) = [(G/19)G]/[(G/19) + G] = G/20 Official source answer: BONUS because G/20 was not present in the original options. For clean upload, Option A has been corrected to G/20 and marked as the correct answer.