Question Detail
Question
A galvanometer of 50 Ω gives full scale deflection with 2 mA current. To convert it into ammeter, range of 10 A is connected with it, shunt resistance should be
Correct Answer
Option C is the correct answer.
Detailed Explanation
To convert a galvanometer into an ammeter, a small shunt resistance (Rs) is connected in parallel with the galvanometer.Given:Galvanometer resistance (Rg) = 50 ΩFull scale deflection current of galvanometer (Ig) = 2 mA = 2 × 10-3 ADesired full scale current of ammeter (I) = 10 AThe current through the shunt resistance (Is) is I - Ig.Since the shunt is in parallel with the galvanometer, the voltage across them is the same:IgRg = IsRsIgRg = (I - Ig)RsRs = (IgRg) / (I - Ig)Rs = (2 × 10-3 A × 50 Ω) / (10 A - 2 × 10-3 A)Rs = (0.1) / (9.998)Rs ≈ 0.010002 ΩThis value is closest to 0.01 Ω.
Hint
The shunt resistance in an ammeter is connected in parallel with the galvanometer. The voltage across parallel components is equal.