An ammeter needs to be built to measure currents up to 2.0 A . If the coil has a resistance of 25 and requires 1 mA for full-scale deflection, determine the required resistance of the shunt.

Step-by-step solution

Given, maximum current to be measured, I = 2.0 A Resistance of the galvanometer coil, R_g = 25 Current for full-scale deflection, I_g = 1 mA = 10⁻³ A The shunt resistance S required is given by the formula: S = I_g R_g I - I_g Since I_g is very small compared to I , we can approximate I - I_g I S I_g R_g I S = 10⁻³ 25 2.0 S = 12.5 10⁻³ S = 0.0125