An electron of mass m with an initial velocity \(\overrightarrow v= v_0\hat i\)\( ( v_o > 0 ) \) enters in an electric field \(\overrightarrow E = -E_0 \hat i\)\((E_0 = \text{constant}>0)\) at \(t=0\). If \(\lambda_0\), is its de-Broglie wavelength initially, then what will be its de-Broglie wavelength at time \(t\)?
1. \(\frac{\lambda_0}{\left(1+ \frac{eE_0}{mv_0}t\right)}\)
2. \(\lambda_0\left(1+ \frac{eE_0}{mv_0}t\right)\)
3. \(\lambda_0 t\)
4. \(\lambda_0\)

Subtopic:  De-broglie Wavelength |
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When the light of frequency \(2\nu_0\) (where \(\nu_0\) is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is \(v_1\). When the frequency of the incident radiation is increased to \(5\nu_0,\) the maximum velocity of electrons emitted from the same plate is \(v_2.\) What will be the ratio of \(v_1\) to \(v_2\)?

1. \(1:2\) 2. \(1:4\)
3. \(4:1\) 4. \(2:1\)
Subtopic:  Einstein's Photoelectric Equation |
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What is the de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature \(T\) (Kelvin) and mass \(m\)?
1. \(\frac{h}{\sqrt{m k T}}\) 2. \(\frac{h}{\sqrt{3 m k T}}\)
3. \(\frac{2 h}{\sqrt{3 m k T}}\) 4. \(\frac{2 h}{\sqrt{m k T}}\)
Subtopic:  De-broglie Wavelength |
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The photoelectric threshold wavelength of silver is \(3250\times 10^{-10}~\text{m}\). What will be the velocity of the electron ejected from a silver surface by the ultraviolet light of wavelength \(2536\times 10^{-10}~\text{m}\)? (Given \(h= 4.14\times 10^{-15}~\text{eVs}\) and \(c= 3\times 10^{8}~\text{m/s}\))
1. \(\approx 0.6\times 10^{6}~\text{m/s}\)
2. \(\approx 61\times 10^{3}~\text{m/s}\)
3. \(\approx 0.3\times 10^{6}~\text{m/s}\)
4. \(\approx 0.3\times 10^{5}~\text{m/s}\)

Subtopic:  Einstein's Photoelectric Equation |
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If an electron of mass \(m\) with a de-Broglie wavelength of \(\lambda\) falls on the target in an \(X\text-\)ray tube, the cut-off wavelength \((\lambda_0)\) of the emitted \(X\text-\)ray will be:
1. \(\lambda_0 = \frac{2mc\lambda^2}{h}\)
2. \(\lambda_0 = \frac{2h}{mc}\)
3. \(\lambda_0 = \frac{2m^2c^2\lambda^3}{h^2}\)
4. \(\lambda_0 = \lambda\)

Subtopic:  De-broglie Wavelength |
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Photons with energy \(5\) eV are incident on a cathode \(C\) in a photoelectric cell. The maximum energy of emitted photoelectrons is \(2\) eV. When photons of energy \(6\) eV are incident on \(C\), no photoelectron will reach the anode \(A\), if the stopping potential of \(A\) relative to \(C\) is:
1. \(+3\) V
2. \(+4\) V
3. \(-1\) V
4. \(-3\) V

Subtopic:  Einstein's Photoelectric Equation |
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An electron of mass m and a photon have the same energy E. Find the ratio of de-Broglie wavelength associated with the electron to that associated with the photon. (c is the velocity of light)

1. E2m1/2

2. c2mE1/2

3. 1c2mE1/2

4. 1cE2m1/2

 

Subtopic:  De-broglie Wavelength |
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​​​When a metallic surface is illuminated with radiation of wavelength \(\lambda\), the stopping potential is \({V}\). If the same surface is illuminated with radiation of wavelength \(2\lambda\), the stopping potential is \(\frac{{V}}{4}\). The threshold wavelength for the metallic surface is:
1. \(5\lambda\)
2. \(\frac{5}{2} \lambda\)
3. \(3\lambda\)
4. \(4\lambda\)
Subtopic:  Einstein's Photoelectric Equation |
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