Question

The magnetic flux through a coil perpendicular to its plane and directed into paper is varying according to the relation $\phi=(2t^{2}+4t+6)\,m\, Wb$ The emf induced in the loop at $t = 4\, s$ is

• A. $0.12\, V$
• B. $2.4\, V$
• C. $0.02\, V$
• D. $1.2\, V$

Answer 1

Answer: (C)

Given, $\phi = (2t^{2}+4t+6)m\,wb$
As, $\varepsilon=\frac{d\phi}{dt}=\frac{d}{dt} (2t^{2}+4t+6)\, m\,Wb\,s^{-1}$
$=(4t+4)\times 10^{-3}\,V$
At $t=4\,s$
$\varepsilon =(4\times4+4)\times10^{-3}\,V$
$=20\times10^{-3}\, V$
$=0.02\, V$