Question

The magnetic flux through a coil perpendicular to its plane and directed into paper is varying according to the relation $\varphi =$ (2t2 + 4t + 6) mWb. 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)

0.02 V

Answer 2

Given $\varphi = (2t^{2} + 4t + 6)mWb$

As , $\varepsilon = \frac{d\varphi}{dt}$

$= \frac{d}{dt}(2t^{2} + 4t + 6) \times 10^{- 3}Wbs^{- 1}$

$= (4t + 4) \times 10^{- 3}V$

At t = 4s

$\varepsilon = (4 \times 4 + 4) \times 10^{- 3}V$

$= 20 \times 10^{- 3}V = 0.02V$