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Question
Briefly explain the three observed features which can be explained by Einstein’s photoelectric equation.
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Solution
Three observed features which can be explained by this equation are:
(i) Solar cells: Also called photo-voltaic cells. It converts solar radiations to electrical emf.
(ii) Television telecast: The dark and bright light part of images are interpreted as high and low electrical charges as given by photoelectric emission principle. These are further processed and transmitted.
(iii) Burglar alarm: The moment the ultraviolet radiation is cut due to theif, it stops the supply of photons and thus works as ‘off’ mode and the ring bells automatically.
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RELATED QUESTIONS
Define the terms (i) ‘cut-off voltage’ and (ii) ‘threshold frequency’ in relation to the phenomenon of photoelectric effect.
Using Einstein’s photoelectric equation shows how the cut-off voltage and threshold frequency for a given photosensitive material can be determined with the help of a suitable plot/graph.
The frequency and intensity of a light source are doubled. Consider the following statements.
(A) The saturation photocurrent remains almost the same.
(B) The maximum kinetic energy of the photoelectrons is doubled.
The electric field at a point associated with a light wave is `E = (100 "Vm"^-1) sin [(3.0 xx 10^15 "s"^-1)t] sin [(6.0 xx 10^15 "s"^-1)t]`.If this light falls on a metal surface with a work function of 2.0 eV, what will be the maximum kinetic energy of the photoelectrons?
(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)
Consider the situation of the previous problem. Consider the faster electron emitted parallel to the large metal plate. Find the displacement of this electron parallel to its initial velocity before it strikes the large metal plate.
(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)
Which is Einstein’s photoelectric equation?
What does \[\phi_0\] represent in Einstein’s photoelectric equation?
What happens if photon energy is less than the work function?
Which expression gives the threshold frequency?
Which expression gives stopping potential \[V_0\] in terms of frequency?
Why does the maximum kinetic energy of photoelectrons increase when frequency increases?
