An ac source is connected to a capacitor C. Due to decrease in its operating frequency

The magnetic energy stored in an inductor of inductance $$4 ~\mu \mathrm{H}$$ carrying a current of $$2 \mathrm{~A}$$ is :

The net impedance of circuit (as shown in figure) will be :

A closely packed coil having 1000 turns has an average radius of 62.8 cm. If current carried by the wire of the coil is 1 A, the value of magnetic field produced at the centre of the coil will be (permeability of free space $$ = 4\pi \times {10^{ - 7}}$$ H/m) nearly