When an electric of frequency (f) passes through an induction coil of zero ohmic
resistance its inductive reactance becomes 12Ω and if the frequency increased by 20Hz
its inductive reactance becomes 18Ω calculate the current frequency in both cases then
calculate the self-induction coefficient for the coil

a) (40 Hz – 60 Hz – 0.048 H)
b) (60 Hz – 40 Hz – 0.048 H)
c) (40 Hz – 60 Hz – 0.48 H)