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. |
The current conduction in a discharge tube is due to:
1. electrons only
2. +ve ions and –ve ions
3. –ve ions and electrons
4. +ve ions and electrons
If a light of amplitude A and wavelength λ is incident on a metallic surface, then the saturation current flow is proportional to (assume cut-off wavelength = ):
1.
2.
3.
4.
1. | less than \(0.5 ~\text{eV}\). |
2. | \(0.5 ~\text{eV}\). |
3. | greater than \(0.5 ~\text{eV}\). |
4. | the photoelectric effect does not occur. |