NTA Abhyas JEE Main2020PhysicsExperimental PhysicsPractice
In an experiment to determine the resistance of a galvanometer by half deflection method, the circuit shown is used. In one set of readings, if R = 1 0 Ω and S = 4 Ω , then the resistance of the galvanometer is
Options
- A20 3 Ω
- B40 3 Ω
- C50 3 Ω
- D70 3 Ω
Correct answer
A. 20 3 Ω
Step-by-step solution
In 1st case, I 1 = E R + G In 2nd case, I 2 = E R + S G S + G for half deflection, I 2 G = 1 2 I 1 1 2 E R + G = E R + S G S + G S S + G ⇒ G = R S R - S G = 10 × 4 10 - 4 = 20 3 Ω