A metal surface is illuminated by a radiation of wavelength 4500 $$\mathop A\limits^o $$. The ejected photo-electron enters a constant magnetic field of 2 mT making an angle of 90$$^\circ$$ with the magnetic field. If it starts revolving in a circular path of radius 2 mm, the work function of the metal is approximately :
A radioactive nucleus can decay by two different processes. Half-life for the first process is 3.0 hours while it is 4.5 hours for the second process. The effective half-life of the nucleus will be:
The positive feedback is required by an amplifier to act an oscillator. The feedback here means :
A sinusoidal wave y(t) = 40sin(10 $$\times$$ 106 $$\pi$$t) is amplitude modulated by another sinusoidal wave x(t) = 20sin (1000 $$\pi$$t). The amplitude of minimum frequency component of modulated signal is :