If the de-Broglie wavelength of an electron in a Bohr orbit be \(\lambda_B,\) then the total energy in the \(n^{\text{th}}\) orbit is proportional to:
1. \(\lambda_B\) 2. \({\dfrac{1}{\lambda_B}}\)
3. \(\lambda_B^{~2}\) 4. \({\dfrac{1}{\lambda_B^{~2}}}\)

Subtopic:  De-broglie Wavelength |
 51%
Level 3: 35%-60%

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Which, of the following circuits, can be used for measuring the stopping potential?
1.  
2.
3.
4.
Subtopic:  Photoelectric Effect: Experiment |
Level 3: 35%-60%

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Photons, emitted by excited hydrogen atoms undergoing the transition corresponding to the \(1^{\text{st}}\) line of the Balmer series, are incident on a photocathode whose work-function is \(1~\text{eV}.\) As a result,
1. electrons emitted have a maximum kinetic energy of \(0.9~\text{eV}\)
2. electrons emitted have a maximum kinetic energy of \(2.9~\text{eV}\)
3. electrons emitted have a maximum kinetic energy of \(1.9~\text{eV}\)
4. electrons are not emitted
Subtopic:  Einstein's Photoelectric Equation |
 64%
Level 2: 60%+

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The correct unit of the quantity \(hc\) (\(h\text:\) Planck's constant, \(c\text:\) speed of light in vacuum), is:
1. \(\text{eV}/\mathring{A}\) 2. \(\text{eV}\text-\mathring{A}\)
3. \(\text{eV}\text-{\text s}\) 4. \(\text{eV}/{\text s}\)
Subtopic:  Particle Nature of Light |
 73%
Level 2: 60%+

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During an experiment on the photoelectric effect, it was observed that (monochromatic light) photons incident on a photocathode, ejected electrons whose minimum de-Broglie wavelength was \(6.2~\mathring{A}.\) The work-function of the surface was \(1~\text{eV}.\) The energy of the incident photons was: \(\Bigg(\)one can use the formula \(\lambda_{dB}={\Large\frac{12.4}{\sqrt{E_k}}}\mathring{A}\Bigg)\)
1. \(101~\text{eV}\)
2. \(3~\text{eV}\)
3. \(4~\text{eV}\)
4. \(5~\text{eV}\)
Subtopic:  Photoelectric Effect: Experiment |
Level 3: 35%-60%

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When an electron makes a transition from the state \(n\) to \((n-1)\) the change in the de-Broglie wavelength of the electron: \(\Delta\lambda=|\lambda_n-\lambda_{n-1}|\)
varies with large \(n\) as:
1. \(\dfrac{1}{n}\) 2. \(\dfrac{1}{n^2}\)
3. \(\dfrac{1}{n^4}\) 4. \(n^0,\text{ constant}\)
Subtopic:  De-broglie Wavelength |
Level 3: 35%-60%

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A beam of neutrons (mass - \(m,\) kinetic energy - \(E\)) is split into two beams by a partial reflection and then the two beams (beam-\(1,\) beam-\(2\)) travel distances \(d_1,d_2\) before being recombined. The neutrons are regarded as wavelike, and their energies (or wavelengths) are not affected by reflection or transmission.
                 
When the path difference is changed by \(\delta,\) consecutive minima are observed in the neutron counting rates. This value of \(\delta\) is \(\Big(\hbar={\large\frac{h}{2\pi}},h=\text{Planck's constant}\Big)\):
1. \({\Large\frac{h}{\sqrt{2mE}}}\)
2. \({\Large\frac{\hbar}{\sqrt{2mE}}}\)
3. \({\Large\frac{h}{2\sqrt{2mE}}}\)
4. \({\Large\frac{\hbar}{2\sqrt{2mE}}}\)
Subtopic:  De-broglie Wavelength |
 55%
Level 3: 35%-60%

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A beam of neutrons (mass - \(m,\) kinetic energy - \(E\)) is split into two beams by a partial reflection and then the two beams (beam-\(1,\) beam-\(2\)) travel distances \(d_1,d_2\) before being recombined. The neutrons are regarded as wavelike, and their energies (or wavelengths) are not affected by reflection or transmission.

The phase difference between the neutrons in beam-\(1\) and beam-\(2\) due to the path difference is \(\Big(\hbar={\large\frac{h}{2\pi}}\Big)\):
1. \({\Large\frac{\sqrt{2mE}}{\hbar}}(d_1-d_2)\) 2. \({\Large\frac{\sqrt{2mE}}{\hbar}\frac{(d_1-d_2)}{2}}\)
3. \({\Large\frac{\sqrt{2mE}}{\hbar}\frac{(d_1+d_2)}{2}}\) 4. \({\Large\frac{\sqrt{2mE}}{2\pi\hbar}}(d_1-d_2)\)
Subtopic:  De-broglie Wavelength |
Level 3: 35%-60%

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A beam of neutrons (mass - \(m,\) kinetic energy - \(E\)) is split into two beams by a partial reflection and then the two beams (beam-\(1,\) beam-\(2\)) travel distances \(d_1,d_2\) before being recombined. The neutrons are regarded as wavelike, and their energies (or wavelengths) are not affected by reflection or transmission.

The wavelength of the neutrons is (\(h\)-Planck's constant):
1. \(\Large{\sqrt\frac{mh^2}{2E}}\) 2. \(\Large{\sqrt\frac{h^2}{2mE}} \)
3. \(\Large{\sqrt\frac{2h^2}{mE}}\) 4. \(\Large{\sqrt\frac{2mh^2}{E}}\)
Subtopic:  De-broglie Wavelength |
 81%
Level 1: 80%+

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Light, corresponding to the most probable wavelength in the spectrum of a blackbody at \(6000~\text K,\) is incident onto a photocathode of work function \(1.5~\text{eV}.\) Take Wien's constant as \(3~\text{mm-K}\) and \(hc=1240~\text{eV-nm}.\)The energy of the fastest photoelectrons emitted is (nearly):
1. \(1~\text{eV}\)
2. \(2.5~\text{eV}\)
3. \(0.5~\text{eV}\)
4. \(4~\text{eV}\)
Subtopic:  Einstein's Photoelectric Equation |
 69%
Level 2: 60%+

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