Question

question is in attachment........​

Answer 1

answer : option (c) 67 units

explanation : magnetic flux linked with the coil is given by, $\phi=8t^2+3t+5$

we know, induced emf is the negative of rate of change of magnetic flux with respect to time.

e.g., $\xi_{in}=-\frac{d\phi}{dt}$

so, first of all, differentiate magnetic flux with with respect to time,

e.g., $\frac{d\phi}{dt}=16t+3$

at t = 4, $\frac{d\phi}{dt}=16\times4+3=67$

so, induced emf = - $\frac{d\phi}{dt}$ at t = 4

= -67 units

hence, magnitude of induced emf in the coil at the fourth second will be 67 units.

Answer 2

Answer:

OPTION C

Step-by-step explanation:

Differentiate change of flux with respect to time .

Let dl = 8 t² + 3 t + 5

Differentiating we find that dl/db = 16 t + 3.

This means that the induced emf changes in the equation 16 t + 3 .

Put t = 4 ,

16 × 4 + 3

= 64 + 3

= 67

Hence 67 units is the answer.