Most asked questions
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Dual Nature Of Radiation And Matter

- Get to know usually which areas are frequently asked in the CBSE exam
1

Energy and momentum of photoelectrons

Energy:

Momentum:


2

Einstein's photoelectric equation

Einstein's photoelectric equation :

The kinetic energy of the photoelectron coming out may be anything between zero and where is the energy supplied to the individual electrons.


3

Stopping potential

The smallest magnitude of the anode potential which just stops the photocurrent is called the stopping potential.
This potential should stop even the ost energitic photoelectron. Hence 
Tha value of maximum kinetic energy should be equal to
We know
4

Calculate the de broglie wavelength of an electron accelerated by a given potential

Example: An electron of charge e and mass m is accelerated from rest by a potential difference V. Find the de-Broglie wavelength.

Solution:


So de-broglie wavelength



5

frequency vs potential

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The maximum kinetic energy of the photoelectrons varies linearly with the frequency of incident radiation, but is independent of its intensity.
For a frequency of of incident radiation, lower than the threshold frequency no photoelectric emission is possible even if the intensity is large.
6

Maximum velocity of photoelectrons


then
The work function of a metal surface is 1 eV. A light of wavelength 3000 is incident on it. The maximum velocity of the photoelectrons is found as:

The maximum K.E with which electrons comes out,


7

De-broglie wavelength

De Broglie's wavelength is the wavelength associated with a massive particle,hypothesized by De Broglie that explains Bohr's quantised orbits by bringing in the wave-particle duality.  It is written as
(de broglie wavelength)