Q11.29Multiple choice
Consider a 20 W bulb emitting light of wavelength 5000 A and shining on a metal surface kept at a distance 2m. Assume that the metal surface has work function of 2 eV and that each atom on the metal surface can be treated as a circular disk of radius ° 1.5 A .
- (i)Estimate no. 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 atomc 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? [Hint: Time calculated in part (iii) is from classical consideration and you may further take the target of surface area say 1cm2 and estimate what would happen?]