A common transistor radio set requires 12 V (D.C.) for its operation. The D.C. source is constructed by using a transformer and a rectifier circuit, which are operated at 220 V (A.C.) on standard domestic A.C. supply. The number of turns of secondary coil are 24, then the number of turns of primary are ___________.

The coefficient of static friction between a wooden block of mass 0.5 kg and a vertical rough wall is 0.2. The magnitude of horizontal force that should be applied on the block to keep it adhere to the wall will be _________ N. [g = 10 ms^$$-$$2]

A resonance circuit having inductance and resistance 2 $$\times$$ 10^$$-$$4 H and 6.28$$\Omega$$ respectively oscillates at 10 MHz frequency. The value of quality factor of this resonator is ___________. [$$\pi$$ = 3.14]

In connection with the circuit drawn below, the value of current flowing through 2 k$$\Omega$$ resistor is _________ $$\times$$ 10^$$-$$4 A.