Concepts Of Physics MCQ Edition [Volume 2]PhysicsPermanent Magnets
A tangent galvanometer is directly connected to an ideal battery. If the coil's number of turns is doubled, the deflection will
Options
- Aeither increase or decrease
- Bremain unchanged
- Cdecrease
- Dincrease
Correct answer
B. remain unchanged
Step-by-step solution
The magnetic field at the center of the coil of a tangent galvanometer is given by B = ₀ N I 2r . The current through the coil is I = V R , where V is the voltage of the ideal battery and R is the resistance of the coil. The resistance of the coil is proportional to the total length of the wire, which is proportional to the number of turns N (assuming the radius r of the coil is constant). Let R = c N , where c is a constant. Substituting I in the expression for B , we get: B = ₀ N 2r ( V c N ) = ₀ V 2 r c This sho