Term
| what is the credit of Davisson and Germer ? |
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Definition
in 1927 they first proved the wave nature of
material particle |
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Term
| describe the experiment of davisson and germer in simple words . |
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Definition
[image]
diagram of the
experimental setup used by Davisson and
Germer it consisted of a nickel chloride
crystal the target an electron gun G and
a detector the electron gun produced a
beam of electrons .The electron gun used
by them consisted of a tungsten filament
F and high and low tension batteries. The
low tension battery was used to heat the
filament. The red hot filament produced
an electron beam .A high tension battery
was provided to accelerate the electron
beam the detector or the electron
collector moved on a graduated circular
scale, a sensitive galvanometer was also
connected to the detector. How did they
perform the experiment:
the electron beam was made to pass
through a pinhole and made to strike the
crystal normally the electrons scattered
in all directions acting like waves. they
observed that at certain angles the
detector indicated a peak in the
intensity of the scattered electron beam
this maximum intensity was due to
constructive interference a phenomenon
confined only to waves thus the
experimental approved the wave nature of
electrons . |
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Term
| what about the result of the exp ? |
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Definition
[image]
Davisson and Germer plotted a graph
taking the angle between the incident
and scattered direction of the electron
beam Phi along the y axis and the
intensity of the scattered beam at
different values of accelerated
potentials along the x axis the nature
of the graph is shown here from the
experimental curves obtained the
following conclusions were drawn-
1.intensity of scattering depends upon the
angle of scattering Phi
2. a bump or kink
occurs in certain angles for each potential
3.this bump or kink
increases as the accelerating potential
difference is increased
4.At 54 volts this
bump is maximum and it forms at the angle of 50 degrees then it distorted on
further increase of potential difference
this peak indicated the wave behavior of
the electrons thus the experiment verifies
de-Broglie's hypothesis of wave nature of matter particles. |
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Term
who first said that the wave nature of matter
might be investigated by electron scattering experiment on crystalline solid( which suggestion was followed by davisson-germer later)? |
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Definition
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Term
| tell the specialty about the voltage 54 V and angle 50 degrees . |
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Definition
| this combination of 54 volt and 50 degree makes the intensity maximum than all other maxima obtained at other voltages. |
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Term
| BUT how we can tell that electron has wave nature ? |
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Definition
| In this experiment nickel crystal makes parallel layers and if electron has wave nature they collide with the layers and there is a path difference due to it, this causes interference. |
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Term
| how from this experiment de Broglie's hypothesis is proved ? |
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Definition
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Term
| derive the general relationship between the wavelength and applied voltage . |
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Definition
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Term
| what is wave velocity or phase velocity? |
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Definition
The phase velocity of a wave is the rate at which the wave propagates in some medium. This is the velocity at which the phase of any one frequency component of the wave travels. For such a component, any given phase of the wave (for example, the crest) will appear to travel at the phase velocity.
[image]
The red square moves with the phase velocity, and the green circles propagate with the group velocity. |
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Term
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Definition
The group velocity of a wave is the velocity with which the overall envelope shape of the wave's amplitudes—known as the modulation or envelope of the wave—propagates through space
[image]
the velocity with which a wave packet associated with the moving particle travels is called the group velocity. |
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Term
| derive the expression of wave velocity. |
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Definition
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Term
| what is the relation between the velocity of the particle and wave associated with it. |
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Definition
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Term
| the velocity of advancement of a monochromatic wave in a medium is known as |
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Definition
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Term
| true or false :according to the theory of de Broglie particle and its associated wave can not travel together. |
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Definition
| true. yes according to Broglie's theory matter wave will leave the matter behind during propagation ,But in the real world this is a conflicting idea so practically it is not true. then schrodinger gave the idea of wave packet and said moving particle is associated with a number of waves and not a single wave. |
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Term
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Definition
In physics, a wave packet (or wave train) is a short "burst" or "envelope" of localized wave action that travels as a unit. A wave packet can be analyzed into, or can be synthesized from, an infinite set of component sinusoidal waves of different wavenumbers, with phases and amplitudes such that they interfere constructively only over a small region of space(where the particle is located ), and destructively elsewhere.
a wave packet is the resultant of group of waves(slightly differing in velocity and wavelength). |
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Term
| what is the relation between group velocity and wave velocity. |
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Definition
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Term
establish the relation between group velocity
and particle velocity. |
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Definition
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Term
| true or false : the de Broglie wave group associated with a moving particle travels with the same velocity as the particle. |
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Definition
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