An ammeter is to be constructed which can read currents up to 2.0A. If the coil has a resistance of `25(Omega)`and takes 1mA for full-scale deflection, what should be the resistance of the shunt used?

Explanation

`g = 25W i_g = 1mA
i_g = 2A s=?
Potential across AB is same
` = 25 xx (10^-3) = (2 - (10^-3)) S `
` S = (25 xx (10^-3))/ (2 - (10^-3)) = (25 xx (10^-3))/1.999 `
` = 12.5 xx (10^-3)= 1.25 xx (10^-2)` .