A photoelectric surface is illuminated successively by the monochromatic light of wavelength \(\lambda\) and \(\frac{\lambda}{2}\). If the maximum kinetic energy of the emitted photoelectrons in the second case is \(3\) times that in the first case, the work function of the surface of the mineral is:
[\(h\) = Plank’s constant, \(c\) = speed of light]
1. \(\frac{hc}{2\lambda}\)
2. \(\frac{hc}{\lambda}\)
3. \(\frac{2hc}{\lambda}\)
4. \(\frac{hc}{3\lambda}\)
1. | \(6\lambda\) | 2. | \(4\lambda\) |
3. | \(\dfrac{\lambda}{4}\) | 4. | \(\dfrac{\lambda}{6}\) |
When the energy of the incident radiation is increased by \(20\%\), the kinetic energy of the photoelectrons emitted from a metal surface increases from \(0.5~\text{eV}\) to \(0.8~\text{eV}\). The work function of the metal is:
1. \(0.65~\text{eV}\)
2. \(1.0~\text{eV}\)
3. \(1.3~\text{eV}\)
4. \(1.5~\text{eV}\)
For photoelectric emission from certain metals, the cutoff frequency is \(\nu\). If radiation of frequency \(2\nu\) impinges on the metal plate, the maximum possible velocity of the emitted electron will be:
(\(m\) is the electron mass)
1. | \(\sqrt{\dfrac{h\nu}{m}}\) | 2. | \(\sqrt{\dfrac{2h\nu}{m}}\) |
3. | \(2\sqrt{\dfrac{h\nu}{m}}\) | 4. | \(\sqrt{\dfrac{h\nu}{2m}}\) |
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. | \(5~\text{V}\) |
The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200 nm falls on it, must be:
1. 2.4 V
2. -1.2 V
3. -2.4 V
4. 1.2 V
When photons of energy h fall on an aluminium plate (of work function E0), photoelectrons of maximum kinetic energy K are ejected. If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be:
1.
2. 2K
3. K
4. K+h