An ammeter with a range of 0 to 100 µA has an internal resistance of 100 Ω. For extending its range to 0 to 500 µA, the shunt resistance required is
An ammeter with a range of 0 to 100 µA has an internal resistance of 100 Ω. For extending its range to 0 to 500 µA, the shunt resistance required is
Right Answer is:
25 Ω
SOLUTION
Full scale deflection current (Im) = 100 µA = 1 × 10−4 A
Internal Resistance Rm = 100 Ω
After range extension, Ammeter current (I) = 500 µA = 5 × 10−4 A
Multiplication factor of ammeter is given by
m = I/Im = (5 × 10−4 A)/(1 × 10−4 A)
m = 5
The shunt resistance of the ammeter can be calculated as
Rsh = Rm/(m − 1) = 100/(5 − 1)
Rsh = 25Ω