JEE MAIN - Physics (2022 - 25th July Evening Shift - No. 25)
Magnetic flux (in weber) in a closed circuit of resistance 20 $$\Omega$$ varies with time t(s) at $$\phi$$ = 8t2 $$-$$ 9t + 5. The magnitude of the induced current at t = 0.25 s will be ____________ mA.
Answer
250
Explanation
$$R = 20\,\Omega $$
$$\phi = 8{t^2} - 9t + 5$$
$$\varepsilon = \left| { - {{d\phi } \over {dt}}} \right| = |16t - 9| = |16(0.25) - 9| = 5$$
$$i = {\varepsilon \over R} = {5 \over {20}} = 0.25\,A = {{0.25} \over {{{10}^3}}} \times {10^3}\,A = 250\,mA$$
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