In a series circuit containing a 20 Ω resistor and an unknown inductor, the rms current is 1.2 A at 500 Hz and also 1.2 A at 2000 Hz when a fixed 0.1 µF capacitor is used. The supply voltage is kept constant. Calculate the inductance of the coil.
a) 0.025H
b) 2.5H
c) 0.25H
d) 0.063H