An `AC` source of variable frequency `f` is connected to an `LCR` series circuit. Which one of the graphs in figure represents the variation of current of current `I` in the circuit with frequecy `f`?

Options

A.
B.
C.
D.

Answer

D

Explanation

The current in an L-C-R circuit is given by
`l=(V)/([R^(2)+(omegaL-(1)/(omegaC))^(2)]^(1//2))`, where `omega=2pif`
thus, l increases with an increase in `omega` upto a value given by,` omega=omega_(c)` `i`. At `omega=omega_(c)`, we have
`omegaL=(1)/(omegaC)implies omega_(c)=(1)/(sqrt(LC))`
where l is maximum l is maximum. At `omega gt omega_(c)` l again starts decreasing with an increase in `omega`.