A sound wave is travelling with a frequency of $$50 \mathrm{~Hz}$$. The phase difference between the two points in the path of a wave is $$\frac{\pi}{3}$$. The distance between those two points is (Velocity of sound in air $$=330 \mathrm{~m} / \mathrm{s}$$ )

A logic gate which gives output 'HIGH' only when its two input terminals are at different logic levels with respect to each other is

A circular coil of radius '$$R$$' has '$$N$$' turns of a wire. The coefficient of self induction of the coil will be ( $$\mu_0=$$ permeability of free space)

An a.c. source of angular frequency '$$\omega$$' is fed across a resistor '$$R$$' and a capacitor '$$C$$' in series. The current registered is I. If now the frequency of source is changed to $$\frac{\omega}{3}$$ (but maintaining the same voltage), the current in the circuit is found to be halved. The ratio of reactance to resistance at the original frequency '$$\omega$$' will be