NCERT Physics Class 12 Exemplar Ch 11 Dual Nature of Radiation and Matter Part 5

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29 Consider a 20 W bulb emitting light of wavelength And shining on a metal surface kept at a distance . Assume that the metal surface has work function of and that each atom on the metal surface can be treated as a circular disk of radius

(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

(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?] .

Ans:

photoelectric emission

Photoelectric Emission

photoelectric emission

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