JEE Main201912 Apr 2019Evening ShiftPhysicsCurrent ElectricityActual
A moving coil galvanometer, having a resistance G , produces full scale deflection when a current I G flows through it. This galvanometer can be converted into (i) an ammeter of range 0 to I o I 0 > I g by connecting a shunt resistance R A to it and (ii) into a voltmeter of range 0 to V V = G I 0 by connecting a series resistance R V to it. Then,
Options
- AR A R V = G 2 I 0 - I g I g and R A R V = I g I 0 - I g 2
- BR A R V = G 2 and R A R V = I g I 0 - I g
- CR A R V = G 2 I g I 0 - I g and R A R V = I 0 - I g I g 2
- DR A R V = G 2 and R A R V = I g I 0 - I g 2
Correct answer
D. R A R V = G 2 and R A R V = I g I 0 - I g 2
Step-by-step solution
For ammeter: I 0 - I G × R A = I G × G ⇒ I 0 = I G × G + R A R A For voltmeter: V 0 = I G G + R V ∵ V 0 = I 0 × G ⇒ I G × G + R V = I G × G + R A × G R A ⇒ R A × G + R V × R A = G 2 + R A × G ⇒ R V R A = G 2 Again, R A R V = I G × G I 0 - I G × I G I 0 - I G × G = I G 2 I 0 - I G 2