A galvanometer has resistance of 400 Ω Ω and deflects full scale for current of 0.2 mA through it. The shunt resistance required to convert it into 3 A ammeter is
Text Solution
Verified by ExpertsThe correct answer is:
A
As shown if i is the maximum current, then a part i g should pass through G and rest i – i g through S. Potential across G and S is same, therefore
i g × G = (i – i g ) × S
⇒ S = 
Given, G = 400 Ω Ω , i g = 0.21 mA = 0.2 × 10 –3 A,
i = 3A
∴ S = 
= 0.027 Ω Ω
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