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The following graph shown the variation of stopping potential V0 with the frequency v of the incident radiation for two photosensitive metals P and Q:
(i) Explain which metal has smaller threshold wavelengths.(ii) Explain, giving reason, which metal emits photoelectrons having smaller kinetic energy.
(iii) If the distance between the light source and metal P is doubled, how will the stopping potential change?
(i) Suppose the frequency of incident radiations of metal Q and P be v0 and v0
’ respectively.
E = hv0
(iii) Stopping potential remains unaffected because the value of stopping potential for a given metal surface does not depend on the intensity of the incident radiation. It depends on the frequency of incident radiation.
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CONCEPT:
- de-Broglie wavelength: The wavelength that is associated with an object in relation to its momentum and mass is known as de Broglie wavelength.
- The de-Broglie wavelength of an electron is given by
λ = h/ √ 2mev
- here. λ is the wavelength of an electron.
h = 6.63 x 10-34
me = mass of an electron
v = potential difference
EXPLANATIONS:
we know
Plancks constant (h) = 6.63 x 10-34.
Volt = 100 v
Mass of electron (me ) = 9.1 x 10-31..
Putting all these values in λ = h/√ 2mev
6.63 x 10-34/√ 2 x 9.1 x 10-31 x 100
0.123 nm
Option 1 is correct.
Let's discuss the concepts related to Atoms and De Broglie’s Explanation of Bohr’s Second Postulate of Quantisation. Explore more from Physics here. Learn now!
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