To convert a galvanometer of resistance G and full-scale deflection current $I_g$ into an ammeter of

Question

To convert a galvanometer of resistance G and full-scale deflection current $I_g$ into an ammeter of range $0$ to $I$, a shunt resistance S is connected in parallel. What is the value of S?

Professor PC Thomas Classes · Answer

For parallel connection, potential difference is the same: $I_g G = (I - I_g) S \implies S = \frac{I_g G}{I - I_g}$.