The magnetic flux `(phi)` linked with a coil depends on time `t` as `phi=at^(n)` , where a and `n` are constants. The emf induced in coil is `e` .
(i) If `0ltnltI,e=0`
(ii) If `0ltnltI,een0` and `|e|` decreases with time
(iii) If `ngtI,e` is constant
(iv) If `nltI,|e|` increases with time

Options

A. `(i),(iii)`
B. `(ii), (iii), (iv)`
C. `(i), (ii)`
D. `(ii), (iv)`

Answer

D

Explanation

`phi=at^(n)`
`|e|=ant^(n-1)`
For `0ltnlt1` , `|e|=(an)/(t^(1-n))`
As `n` increases from `0` to `1` , `|e|` decreases
For `ngt1` , `|e|=ant^(n-1)` , `|e|` increases