Light of wavelength \(500~\text{nm}\) is incident on metal with work function \(2.28~\text{eV}\). The de-Broglie wavelength of the emitted electron is:
1. | \(< 2.8\times 10^{-10}~\text{m} \) | 2. | \(< 2.8\times 10^{-9}~\text{m}\) |
3. | \(\geq 2.8\times 10^{-9}~\text{m}\) | 4. | \(\leq 2.8\times 10^{-12}~\text{m}\) |
Radiation of energy \(E\) falls normally on a perfectly reflecting surface. The momentum transferred to the surface is:
(\(c\) = velocity of light)
1. \(E \over c\)
2. \(2E \over c\)
3. \(2E \over c^2\)
4. \(E \over c^2\)
1. | \(6\lambda\) | 2. | \(4\lambda\) |
3. | \(\dfrac{\lambda}{4}\) | 4. | \(\dfrac{\lambda}{6}\) |
Which of the following figures represent the variation of the particle momentum and the associated de-Broglie wavelength?
1. | |
2. | |
3. | |
4. | |
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. \(1.5~\text{eV}\)
If the kinetic energy of the particle is increased to \(16\) times its previous value, the percentage change in the de-Broglie wavelength of the particle is:
1. \(25\)
2. \(75\)
3. \(60\)
4. \(50\)
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. | \(\sqrt{\dfrac{h\nu}{2m}}\) |
A \(200~\text{W}\) sodium street lamp emits yellow light of wavelength \(0.6~\mu\text{m}\). Assuming it to be \(25\%\) efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is:
1. \(1.5\times 10^{20}\)
2. \(6\times 10^{18}\)
3. \(62\times 10^{20}\)
4. \(3\times 10^{19}\)
An \(\alpha\text-\)particle moves in a circular path of radius \(0.83~\text{cm}\) in the presence of a magnetic field of \(0.25~\text{Wb/m}^2\). The de-Broglie wavelength associated with the particle will be:
1. \(1~\mathring{\text{A}}\)
2. \(0.1~\mathring{\text{A}}\)
3. \(10~\mathring{\text{A}}\)
4. \(0.01~\mathring{\text{A}}\)