Two radiations of photons energies \(1\) eV and \(2.5\) eV, successively illuminate a photosensitive metallic surface of work function \(0.5\) eV. The ratio of the maximum speeds of the emitted electrons is:
1. \(1:2\)
2. \(1:1\)
3. \(1:5\)
4. \(1:4\)
If the momentum of an electron is changed by \(P,\) then the de-Broglie wavelength associated with it changes by \(0.5\%.\) The initial momentum of an electron will be:
1. \(400P\)
2. \(\frac{P}{100}\)
3. \(100P\)
4. \(200P\)
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. | \(5~\text{V}\) |
When monochromatic radiation of intensity I falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are N and T respectively. If the intensity of radiation is 2I, the number of emitted electrons and their maximum kinetic energy are respectively:
1. 2N and T
2. 2N and 2T
3. N and T
4. N and 2T
What did Einstein prove by the photo-electric effect?
1. \(E = h\nu\)
2. \(K.E = \frac{1}{2}mv^2\)
3. \(E= mc^2\)
4. \(E = \frac{-Rhc^2}{n^2}\)
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
1. | \(1.2\) eV | 2. | \(0.98\) eV |
3. | \(0.45\) eV | 4. | \(0\) eV |
According to Einstein's photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is:
1. | 2. | ||
3. | 4. |