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Question
A closely wound circular coil of radius 0.02 m is placed perpendicular to the magnetic field. When the magnetic field is changed from 8000 T to 2000 T in 6 s, an emf of 44 V is induced in it. Calculate the number of turns in the coil.
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Solution
Given data:
radius r = 0.02 m
Q = 90° – 90° = 0°
B1 = 8000 T, B2 = 2000 T
dt = 68
ε = 68V
n = ?
ε = nA cos θ `"dB"/"dt"`
`44 = "n" xx pi xx 0.02 xx 0.02 xx cos theta xx ((8000 - 2000)/6)`
`44 = "n" xx 22/7 xx 4 xx 10^4 xx 1 xx 6000/6`
n = `(44 xx 7 xx 6)/(22 xx 4 xx 10^-4 xx 6000)`
`= 7/(2 xx 10^-1) = 70/2`
n = 35 turns
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