In an interference experiment the ratio of amplitudes of coherent waves is $${{{a_1}} \over {{a_2}}} = {1 \over 3}$$ . The ratio of maximum and minimum intensities of fringes will be :

An alternating voltage v(t) = 220 sin 100 $$\pi $$t volt is applied to a purely resistance load of 50$$\Omega $$ . The time taken for the current to rise from half of the peak value to the peak value is :

Two particles move at right angle to each other. Their de-Broglie wavelengths are $$\lambda _1$$ and $$\lambda _2$$ respectively. The particles suffer perfectly inelastic collision. The de-Broglie wavelength $$\lambda _2$$ of the final particle, is given by :

The wavelength of the carrier waves in a modern optical fiber communication network is close to :