Question

The magnetic flux linked with a coil at any instant ‘t’ is given by $\varphi =5t^3-100t+300,$ the e.m.f. induced in the coil at t = 2 second is

• A. – 40 V
• B. 40 V
• C. 140 V
• D. 300 V

Answer 1

The correct option is B 40 V

$e=-\frac{d\varphi }{dt}=-\frac{d}{dt}(5t^3-100t+300)$
$=-(15t^2-100)$ at t=2sec; e=40 V