A long solenoid of diameter 0.1 m has $2 imes 10^4$ turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0A from 4 A in 0.05 s. If the resistance of the coil is $10\pi^2$ Ω, the total charge flowing through the coil during this time is :

Question

A long solenoid of diameter 0.1 m has $2 	imes 10^4$ turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0A from 4 A in 0.05 s. If the resistance of the coil is $10\pi^2$ Ω, the total charge flowing through the coil during this time is :

Dr. Abubacker · Accepted Answer

[Solution] $Q = \frac{N\Delta\phi}{R} = \frac{100 	imes \mu_0 n I \pi r^2}{R} = \frac{100 	imes 4\pi 	imes 10^{-7} 	imes 2 	imes 10^4 	imes 4 	imes \pi 	imes 10^{-4}}{10\pi^2} = 32$ μC. Answer (3).

Explanation

Reviewed by Dr. Abubacker

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