Question
A galvanometer coil has a resistance of 15 Ω and the metre shows full scale deflection for a current of 4 mA. How will you convert the metre into an ammeter of range 0 to 6 A?
Solution
Given, a galvanometer coil.
Resistance on galvanometer, G = 15 Ω
Current pasing through the galvanometer,Ig = 4 mA = 4 x 10–3 A
Current across the ammeter, I = 6 A
Using formula,
Putting values,
Therefore, a resistance of 10mΩ should be connected so as to convert the galvanometer into an ammeter.
Resistance on galvanometer, G = 15 Ω
Current pasing through the galvanometer,Ig = 4 mA = 4 x 10–3 A
Current across the ammeter, I = 6 A
Using formula,
Putting values,
Therefore, a resistance of 10mΩ should be connected so as to convert the galvanometer into an ammeter.