Question

The magnetic flux linked with a coil, in webers, is given by the equation $\varphi =8t^2-3t+5$. Then the magnitude of induced emf at $4$ sec will be ..

• A. $15$ v
• B. $-61$ v
• C. $13$ v
• D. $21$ v

Answer 1

The correct option is B $-61$ v

$\begin{array}{c}Inducedemf\xi =-\frac{d\Phi }{dt},where\Phi =totalmagneticFluxthroughthecoil.\\ \xi =\frac{-d\left(8t^2+3t+5\right)}{dt}\\ =-16t+3\\ =-16\times 4+3\\ =-61v\\ Hence,\\ optionCiscorrectanswer\end{array}$