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 Å is/are:
1. None
2. A only
3. A and B only
4. All the three metals
A photosensitive metallic surface has a work function of hν0. If photons of energy 2hν0 fall on this surface, the electrons come out with a maximum velocity of 4 × 106 m/s. When the photon energy is increased to 5hν0, then the maximum velocity of photoelectrons will be:
1. 2 ×107 m/s
2. 2 × 106 m/s
3. 8 × 105 m/s
4. 8 × 106 m/s
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 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 \(E_0\). |
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. \(10^{5}~\text{V}\)
The de-Broglie wavelength of a particle accelerated by a 150 volt potential difference is 10-10 m. What will its wavelength be if it is accelerated by a 600 volt potential difference?
1. 0.25
2. 0.5
3. 1.5
4. 2
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. \(\frac{n-1}{n-3} \lambda \)
2. \(\frac{n}{n-3} \lambda \)
3. \(\frac{n-3}{n-1} \lambda \)
4. \(\frac{n+1}{n-3} \lambda\)
A source S1 is producing, 1015 photons per sec of wavelength 5000 Å. Another source S2 is producing 1.02×1015 photons per second of wavelength 5100 Å. Then the ratio of the power of S2 to the power of S1 is equal to:
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 |