Consider a 20 W bulb emitting light of wavelength 5000 and shining on a metal surface kept at a distance of 2 m. Assume that the metal surface has a work function of 2 eV and that each atom on the metal surface can be treated as a circular disk of radius 1.5 .
(i) Estimate the 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 the atomic disk receive within the time duration calculated in (iii) above?
(v) Can you explain how the photoelectric effect was observed instantaneously?
© 2026 GoodEd Technologies Pvt. Ltd.
