A $400$ Hz sinusoidal voltage with a max. amplitude of $100$V at t$=0$ is applied across the terminals

of an inductor. The maximum amplitude of the steady$-$state current in the inductor is $20$A$.$

a$)$ If the phase angle of the voltage is zero, what is the phase angle of the current?

b$)$ What is the inductive reactance of the inductor?

c$)$ What is the inductance of the inductor, in millihenries?

d$)$ What is the impedance of the inductor?

Answer: a$)90$; b$)5$; c$)1\mathrm{.}99$ mH; d$)$ j$5.$