An ammeter with range 0 to 2 mA has internal resistance of 10 Ω. What is the value of shunt resistance in order to increase the range of ammeter to 100 A?
- A. 200 µΩ
- B. 200 mΩ
- C. 2 µΩ
- D. 2000 mΩ
Answer: A. 200 µΩ
Explanation: Multiplication factor m = 100 A / 2 mA = 50,000. Shunt resistance Rsh = Rm / (m − 1) ≈ 10 Ω / 50,000 = 0.0002 Ω = 200 µΩ.