Which of the following is not the property of cathode rays:
1. | it produces a heating effect. |
2. | it does not deflect in the electric field. |
3. | it casts a shadow. |
4. | it produces fluorescence. |
1. | cathode rays are streams of negatively charged ions. |
2. | all the mass of an atom is essentially in the nucleus. |
3. | the \(\frac{e}{m}\) of electrons is much greater than the \(\frac{e}{m}\) of protons. |
4. | the \(\frac{e}{m}\) ratio of the cathode ray particles changes when a different gas is placed in the discharge tube. |
A photo-cell is illuminated by a source of light, which is placed at a distance \(d\) from the cell. If the distance becomes \(\dfrac{d}{2}\), then the number of electrons emitted per second will be:
1. same
2. four times
3. two times
4. one-fourth
1. | work function of material |
2. | intensity of incident radiation |
3. | frequency of incident radiation |
4. | wavelength of incident radiation |
The wavelength of light in the visible region is about \(550\) nm (average wavelength) for yellow-green colour. Three materials with work functions are given as Al (\(4.28\) eV), Cu (\(4.65\) eV) and Na (\(2.75\) eV). From which of these photosensitive materials, can you build a photoelectric device that operates with visible light?
1. Al
2. Cu
3. Na
4. none of the above
1. | \(V_0 /2\) | 2. | \(V_0 \) |
3. | \(4V_0 \) | 4. | \(2V_0 \) |
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. |