A coil of inductance 0.50 H and resistance 100`Omega` is connected to a 240 V, 50 Hz ac supply.
(a) What is the maximum current in the coil?
(b) What is the time lag between the voltage maximum and the current maximum?

Explanation

For an LR circuit, if `V=V_(0)sin omega t`
`I=(V_(0))/(sqrt(R^(2)+omega^(2)L^(2))) sin (omega t -phi)`, where `tan phi=(omega L//R)`.
(a) `I_(0)=1.82A`
(b) V is maximum at t = 0, I is maximum at `t=(phi//omega)`.
Now, `tan phi=(2pi vL)/(R ) = 1.571 or phi ~~57.5^(@)`
Therefore, time lag `=(57.5pi)/(180)xx(1)/(2pi xx 50)=3.2 ms`