Question

A galvanometer coil has a resistance of 15 ohm and the metre shows full scale deflection for a current of 4mA. How will you convert the metre into an ammeter of range 0 to 6 A?

Answer 1

Resistance of the galvanometer coil,
G=15×l
Ig=4×10^−3A;
I=6A
A small resistance which is called as shut resistance is connected in parallel , so that the galvanometer is covered into an ammeter.
S=Ig×G/(I−Ig)
=(4×10^−3×15)/(6−4×10^−3)
=0.01Ω
Answer : 0.01Ω