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प्रश्न
Use Einstein's photoelectric equation to show how from this graph,
(i) Threshold frequency, and
(ii) Planck's constant can be determined.
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उत्तर
Einstein's photoelectric equation is (K. E.)max = hv - W
⇒ (K. E.)max = hv - W = eVs
⇒ eVs = hv - W
⇒ `"V"_s = "h"/"e" "v" - "w"/"e""`
⇒ y = mx + c
As we can see a graph can be plotted between stopping potential and frequency of incident photons.
(i) Threshold frequency can be obtained from the graph where the graph cuts the x-axis, i.e. where the value of stopping potential becomes zero.
(ii) As the slope of the graph is `"h"/"e"`, hence by calculating the slope and multiplying it by the value of charge 'e' we can also find the value of plank's constant.
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संबंधित प्रश्न
In an experiment on the photoelectric effect, the slope of the cut-off voltage versus the frequency of incident light is found to be 4.12 × 10−15 Vs. Calculate the value of Planck’s constant.
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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.
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(A) The saturation photocurrent remains almost the same.
(B) The maximum kinetic energy of the photoelectrons is doubled.
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Radiation of frequency 1015 Hz is incident on three photosensitive surfaces A, B and C. Following observations are recorded:
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Surface C: photo emission occurs and photoelectrons have some kinetic energy.
Using Einstein’s photo-electric equation, explain the three observations.
If c is the velocity of light in free space, the correct statements about photon among the following are:
- The energy of a photon is E = hv.
- The velocity of a photon is c.
- The momentum of a photon, ρ = `(h v)/c`
- In a photon-electron collision, both total energy and total momentum are conserved.
- Photon possesses positive charge.
Choose the correct answer from the options given below:
