A long solenoid of radius 2 cm has 100 turns/cm and is surrounded by a 100-turn coil of radius 4 cm having a total resistance of 20Ω .The coil is connected to a galvanometer as shown in figure. If the

Question

A long solenoid of radius 2 cm has 100 turns/cm and is surrounded by a 100-turn coil of radius 4 cm having a total resistance of $20Ω$ .The coil is connected to a galvanometer as shown in figure. If the current in the solenoid is changed from 5 A in one direction to 5 A in the opposite direction, find the charge which flows through the galvanometer in $μ C$ . (Given : $π^{2} = 10$ )

diagram

TestHub · Accepted Answer

B = μ 0 ​ ni = 4 π × 1 0 − 7 × 1 0 4 × 5 = 2 π × 1 0 − 2 T ; flux only through solenoid area A = π ( 0.02 ) 2 . Q = R N ⋅ 2 B A ​ = 20 100 × 2 × 2 π × 1 0 − 2 × 4 π × 1 0 − 4 ​ . With π 2 = 10 : Q = 800 μ C .

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