QJEEM22Phc1aa: JEE Main 2022 Physics - Class 12 JEEM22Phc1aa Solution: In a coil of resistance , the magnetic flux due to an external…

$R = 8\,\Omega$

$\phi = {2 \over 3}(9 - {t^2})$

At $t = 3$ , $\phi = 0$

$\varepsilon = \left| { - {{d\phi } \over {dt}}} \right| = {4 \over 3}t$

$H = \int_0^3 {{{{V^2}} \over R}dt = \int_0^3 {{1 \over 8} \times {{16} \over 9}{t^2}dt} }$

$= {2 \over 9} \times \left( {{{{t^3}} \over 3}} \right)_0^3 = {2 \over {9 \times 3}} \times 27 = 2\,J$