The flux linked with a coil at any instant 't' is given by `phi = 10t^(2) - 50t +250`
The induced emf at `t = 3s` is

Options

A. `10 V`
B. `30 V`
C. `45 V`
D. `90 V`

Answer

A

Explanation

`|e|=(dvarphi)/(dt)=(d)/(dt)(5t^(2)+3t+16)=(10t+3)` When `t=3 sec, e_(3)=(10xx3+3)=33 V`
when `t=4 sec, e_(4)=(10xx4+4)=43 V`
hence emf induced in fourth second
`=e_(4)-e_(3)=43-33=10 V`