Question 45
Current ElectricityA 0 − 10 mA galvanometer with a coil resistance of 30 Ω can be converted to a 0 − 10 A ammeter by using
- A.0.03 Ω series resistor
- B.0.03 Ω shunt resistor
- C.9.99 Ω shunt resistor
- D.9.99 Ω series resistor.
Show the answer and explanation
Answer: B (0.03 Ω shunt resistor)
Explanation
The shunt carries 10 − 0.01 = 9.99 A at the same p.d. as the meter: 9.99R = 0.01 × 30, so R ≈ 0.03 Ω, connected in parallel.