JEE Main2016PhysicsCurrent ElectricityActual
To know the resistance G of a galvanometer by half deflection method, a battery of emf V E and resistance R is used to deflect the galvanometer by angle θ . If a shunt of resistance S is needed to get half deflection the G , R and S are related by the equation:
Options
- AS R + G = R G
- B2 S R + G = R G
- C2 G = S
- D2 S = G
Correct answer
A. S R + G = R G
Step-by-step solution
Let resistance S is connected with galvanometer of resistance G , than I G = V R + G Now, as shown below figure a shunt S is connected in parallel with the galvanometer for half deflection in it, that is I G '   =   I G 2 , than I = V R + G S G + S As, shunt and galvanometer are in parallel then V G = V S I G ' G = I - I G ' S ⇒ I G ' G + S = IS ⇒ I G 2 = I S G + S           ∵ I G ' = I G 2 On, substituting the values of I G and I in above equ