The threshold frequency for a photosensitive metal is \(3.3\times10^{14}~\text{Hz}\). If the light of frequency \(8.2\times10^{14}~\text{Hz}\) is incident on this metal, the cutoff voltage for the photoelectric emission will be:
1. | \(1~\text{V}\) | 2. | \(2~\text{V}\) |
3. | \(3~\text{V}\) | 4. | \(5~\text{V}\) |
Consider a beam of electrons (each electron with energy \(E_0)\) incident on a metal surface kept in an evacuated chamber. Then:
1. | no electrons will be emitted as only photons can emit electrons. |
2. | electrons can be emitted but all with energy, \(E_0\) |
3. | electrons can be emitted with any energy, with a maximum of \(\mathrm{E}_0-\phi\) (\(\phi\) is the work function). |
4. | electrons can be emitted with any energy, with a maximum \(E_0\). |
A light of wavelength \(\lambda \) is incident on the metal surface and the ejected fastest electron has speed \(v.\) If the wavelength is changed to \(\frac{3\lambda}{4},\) then the speed of the fastest emitted electron will be:
1. | \(\sqrt{\frac{4}{3}}v\) | smaller than
2. | \(\sqrt{\frac{4}{3}}\)\(v\) | greater than
3. | \(2v\) |
4. | zero |
The work functions for metals \(A,B,\) and \(C\) are respectively \(1.92\) eV, \(2.0\) eV, and \(5\) eV. According to Einstein's equation, the metals that will emit photoelectrons for a radiation of wavelength \(4100~\mathring{A}\) is/are:
1. None
2. \(A\) only
3. \(A\) and \(B\) only
4. All the three metals
An electron is accelerated from rest through a potential difference of \(V\) volt. If the de Broglie wavelength of an electron is \(1.227\times10^{-2}~\text{nm}\). what will be its potential difference?
1. \(10^{2}~\text{V}\)
2. \(10^{3}~\text{V}\)
3. \(10^{4}~\text{V}\)
4. \(10^{5}~\text{V}\)
In an experiment of the photoelectric effect, the wavelength of incident radiation is . The wavelength of incident radiation is reduced to rd of initial value and the maximum kinetic energy of photoelectron is observed to be n times the previous value. What will be the threshold wavelength for the metal plate?
1. | \(\dfrac{n-1}{n-3} \lambda \) | 2. | \(\dfrac{n}{n-3} \lambda \) |
3. | \(\dfrac{n-3}{n-1} \lambda \) | 4. | \(\dfrac{n+1}{n-3} \lambda\) |
1. | \(1.00\) | 2. | \(1.02\) |
3. | \(1.04\) | 4. | \(0.98\) |
1. | decrease by \(2\) times |
2. | decrease by \(4\) times |
3. | increase by \(4\) times |
4. | increase by \(2\) times |