Q: Consider a 20 W bulb emitting light of wavelength 5000 Å and shining on a metal surface kept at a distance 2 m. Assume that the metal surface has work function of 2 eV and that each atom on the metal surface can be treatment as a circular disk of radius. 1.5 Å.
(i) Estimate number of photons emitted by the bulb per second. [Assume no other losses]
(ii) Will there be photoelectric emission ?
(iii) How much time would be required by the atomic disk to receive energy equal to work function (2 eV) ?
(iv) How many photons would atomic disk receive within time duration calculated in (iii) above ?
(v) Can you explain how photoelectric effect was observed instantaneously ?