Question

The magnetic flux linked with a coil satisfies the relation $\phi= (4t^2 + 6t + 9) Wb$, where $t$ is the time in second. The e.m.f. induced in the coil at $t\, =\, 2$ second is

• A. 22 V
• B. 18 V
• C. 16 V
• D. 40 V

Answer 1

Answer: (A)

22 V

Answer 2

Given $\phi=4 t^{2}+6 t+9$ and $t=2\, s$
We know that $\varepsilon=\frac{d \phi}{d t}$
Here, $\frac{d \phi}{d t}=8 t+6$
$\left(\frac{d \phi}{d t}\right)_{t=2} =8 \times 2+6$
$\varepsilon =22\, V$