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Dual Nature Of Radiation And Matter

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1

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.


2

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
3

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)

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

Lenard's experiment

Wilhelm Hallwachs and Philipp Lenard investigated the phenomenon of photoelectric emission in detail during 1886-1902.
Their observations can be summarised as below:
  • When light is incident on a metal plate, it may cause the electrons to come out of the metal.
  • Hallwachs and Lenard also observed that when the light fell on the emitter plate, no electrons were emitted at all when the frequency of the incident light was smaller than a certain minimum value. This frequency is called threshold frequency.
  • He also observed that different metals have different threshold frequencies.
6

Energy and momentum of photoelectrons

Energy:

Momentum:


7

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.


The graph between and stopping potential (V) of three metals having work functions and in an experiment of photo-electric effect is plotted as shown in the figure. Which of the following statement(s)  correct? [Here is the wavelength of the incident ray].
This question has multiple correct options
A
Ratio of work functions : : : 2 : 4
B
Ratio of work functions : : : 2 : 1
C
is directly proportional to , where is Planck's constant and is the speed of light.
D
The violet colour light can eject photoelectrons from metals 2 and 3.
8
9

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)

10

Heisenberg uncertainty principle

The position and momentum of a particle cannot be simultaneously measured with arbitrarily high precision.