An inductor of 10 mH is connected to a 20V battery through a resistor of 10 k$$\Omega$$ and a switch. After a long time, when maximum current is set up in the circuit, the current is switched off. The current in the circuit after 1 $$\mu$$s is $${x \over {100}}$$ mA. Then x is equal to ___________. (Take e^$$-$$1 = 0.37)

A circular conducting coil of radius 1 m is being heated by the change of magnetic field $$\overrightarrow B $$ passing perpendicular to the plane in which the coil is laid. The resistance of the coil is 2 $$\mu$$$$\Omega$$. The magnetic field is slowly switched off such that its magnitude changes in time as

$$B = {4 \over \pi } \times {10^{ - 3}}T\left( {1 - {t \over {100}}} \right)$$

The energy dissipated by the coil before the magnetic field is switched off completely is E = ___________ mJ.

In the reported figure, two bodies A and B of masses 200 g and 800 g are attached with the system of springs. Springs are kept in a stretched position with some extension when the system is released. The horizontal surface is assumed to be frictionless. The angular frequency will be ____________ rad/s when k = 20 N/m.

The value of aluminium susceptibility is 2.2 $$\times$$ 10^$$-$$5. The percentage increase in the magnetic field if space within a current carrying toroid is filled with aluminium is $${x \over {{{10}^4}}}$$. Then the value of x is _________________.