Tag: physics

Questions Related to physics

In Davisson-Germer experiment, electron gun is coated with oxide of _______ .

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. Barium

  2. Sodium

  3. Potassium

  4. Iron

Show answer
Correct Option: A
Explanation:

The Davisson and Germer experiment consisted of Nickel crystal (target), electron gun and a detector. The electron gun consisted of tungsten filament with high and low tension batteries. The work function of uncoated tungsten filament is 4.5 eV. The coating of Barium oxide on this filament reduces its work function so that electron can be emitted at low temperature.

In Davisson-Germer experiment, the electron beam is made to fall on surface of _________ crystals.

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. Nickel

  2. Iron

  3. Gold

  4. Cesium

Show answer
Correct Option: A
Explanation:

Davisson-Germer experiment was conducted by two American scientists Clinton Davisson and Lester Germer, in 1927, to verify the de Broglie hypothesis that a material particle posses wave nature. 

The electron beam was made to pass through a hole and strike the surface of nickel crystal normally, the electrons scattered in all directions acting like waves. The detector indicated the peak intensity of scattered electrons at certain angle. This maximum intensity was due to constructive interference of two waves. Thus wave nature of electrons was experimentally proved.

Davisson and Germer experiment represents _______ nature of the electron.

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. Wave

  2. Particle

  3. Wave and particle

  4. Doesn't represent any nature

Show answer
Correct Option: A
Explanation:

Davisson-Germer experiment was conducted by two American scientists Clinton Davisson and Lester Germer, in 1927, to verify the de Broglie hypothesis that a material particle posses wave nature. 

The electron beam was made to pass through a hole and strike the nickel crystal normally, the electrons scattered in all directions acting like waves. The detector indicated the peak intensity of scattered electrons at certain angle. This maximum intensity was due to constructive interference of two waves. Thus wave nature of electrons was experimentally proved.

Davisson Germer experiment explained the wave nature of electrons through 

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. Electron diffraction

  2. Electron interference

  3. Electron scattering

  4. Failed to explain wave nature of electrons

Show answer
Correct Option: A
Explanation:

Davisson-Germer experiment was conducted by two American scientists Clinton Davisson and Lester Germer, in 1927, to verify the de Broglie hypothesis that a material particle posses wave nature. They experimentally proved the wave nature of electron through diffraction of electron beam by a nickel crystal.

In experiment of Davisson-Germer, emitted electron from filament is accelerated throguh voltage $V$ then de-Broglie wavelength of that electron will be ________ m .

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. $\cfrac { 2eVm }{ \sqrt { h } } $

  2. $\cfrac { \sqrt { h } }{ 2Vem } $

  3. $\cfrac { \sqrt { 2Vem } }{ h } $

  4. $\cfrac { h }{ \sqrt { 2Vem } } $

Show answer
Correct Option: D
Explanation:

Kinetic energy of the electron will be due to the voltage supplied.

$\cfrac { 1 }{ 2 } m{ v }^{ 2 }=eV$
$v=\sqrt { \cfrac { 2eV }{ m }  } $
We know that the wavelength is obtained as:
$\lambda =\cfrac { h }{ mv } $
$\quad \lambda =\cfrac { h }{ m\sqrt { \cfrac { 2eV }{ m }  }  } =\cfrac { h }{ \sqrt { 2eVm }  } $

If the stationary proton and $\alpha -$particle are accelerated through same potential difference the ratio of their wavelength will be

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. $2$

  2. $1$

  3. $2\sqrt {2}$

  4. $None\ of\ these$

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Correct Option: A

In davisson-Germer experiment an electron beam accelerated with $54$ volt is diffracted at an angle of $$ by a nickel crystal and produced first diffraction maxima. The interatomic distance in Nickel crystal is  

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. $1\mathop A\limits^0 $

  2. $2\mathop A\limits^0 $

  3. $2.15\mathop A\limits^0 $

  4. $3.12\mathop A\limits^0 $

Show answer
Correct Option: C

In Davisson-Germer experiment an electron bear of energy 75 eV falls normally on the surface via crystal If the maxima of order I. _obtained at an angIe $45^o$ to the direction incidentr then the interatomic distance in the lattice palne of the cystal will be-

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. $1.0 \ AA$

  2. $1.56 \ AA$

  3. $1.20 \ AA$

  4. $0.83 \ AA$

Show answer
Correct Option: A
Explanation:

$\begin{array}{l} nb=2d\sin  \theta  \ \frac { { 12.27 } }{ { \sqrt { 75 }  } } =2d\sin  45 \ 1.41=2d\times \frac { 1 }{ { \sqrt { 2 }  } }  \ \therefore d=\frac { { 1.41 } }{ { 1.41 } } =1A^{ ^{ \circ  } } \end{array}$

Hence, the option $A$ is the correct answer.

The wavelength of $L _\alpha$ line in $X-ray$ spectrum of $Pt^{78}$ is $1.32\mathring { A } $ then wavelength of $L _\alpha $ line $X-ray$ spectrum of another unknown element is $4.17\mathring { A } .$ If screening constant for $L _\alpha $ line is $7.4,$ then atomic number of the unknown element is -

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. $78$

  2. $47$

  3. $40$

  4. $35$

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Correct Option: A

Davisson and Germer studied the diffraction from crystal of beams of

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. Alpha particles

  2. Protons

  3. Electrons

  4. Photons

Show answer
Correct Option: C
Explanation:

Davisson and Germer's actual objective was to study the surface of a piece of nickel by directing a beam of electrons at the surface and observing how many electrons bounced off at various angles. They expected that because of the small size of electrons, even the smoothest crystal surface would be too rough and thus the electron beam would experience diffuse reflection.

During the experiment an accident occurred and air entered the chamber, producing an oxide film on the nickel surface. To remove the oxide, Davisson and Germer heated the specimen in a high temperature oven, not knowing that this affected the formerly polycrystalline structure of the nickel to form large single crystal areas with crystal planes continuous over the width of the electron beam. 

When they started the experiment again and the electrons hit the surface, they were scattered by atoms which originated from crystal planes inside the nickel crystal.In 1925, they generated a diffraction pattern with unexpected peaks.

So, the answer is option (C).