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प्रश्न
Two concentric circular loops of radius 1 cm and 20 cm are placed coaxially.
(i) Find mutual inductance of the arrangement.
(ii) If the current passed through the outer loop is changed at a rate of 5 A/ms, find the emf induced in the inner loop. Assume the magnetic field on the inner loop to be uniform.
उत्तर
We know `varphi = "MI"`
And magnetic field at the center of the bigger loop `vec"B" = (mu_o"I")/(2"R") = (4pi xx 10^-7"I")/(2xx20xx10^-2) = pi xx 10^-6"I"`
Flux through the smaller loop
`varphi = "BA"_"s" = (4pixx10^-5"I")/40 xx pi(0.01)^2 = pi^2 xx 10^-10 xx "I"`
`"M" = varphi/"I" = pi^2 xx 10^-10 = 9.86 xx 10^-10 "H"`
Now emf induced
e = `-("d"varphi)/("d""t") = -9.86 xx 10^-10 xx ("d""I")/("d""t")`
e = `-9.86 xx 10^-10 xx 5 = -4.93 xx 10^-9 "V"`
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