Q. No.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. same
2. four times
3. two times
4. one-fourth
| 1. | each emitted electron carries one-quarter of the initial energy. |
| 2. | number of electrons emitted is half the initial number. |
| 3. | each emitted electron carries half the initial energy. |
| 4. | number of electrons emitted is a quarter of the initial number. |
demonstrated that:
| 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. |
Which of the following demonstrates the particle nature of light?
1. photoelectric effect
2. interference
3. refraction
4. polarisation
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. |
When ultraviolet rays strike a metal plate, the photoelectric effect does not occur. It occurs by the incidence of:
1. Infrared rays
2. X-rays
3. Radio wave
4. Lightwave
If particles are moving with the same velocity, then the de-Broglie wavelength is maximum for:
1. proton
2. \(\alpha\text-\)particle
3. neutron
4. \(\beta\text-\)particle
The value of Planck's constant is:
| 1. | \(6.63\times 10^{-34}~\text{J/s}\) | 2. | \(6.63\times 10^{-34}~\text{kg-}\text{m}^2\text{/s}\) |
| 3. | \(6.63\times 10^{-34}~\text{kg-}\text{m}^2\) | 4. | \(6.63\times 10^{-34}~\text{J-s}^2\) |
The total energy of an electron is \(3.555~\text{MeV}.\) Its kinetic energy will be:
1. \(3.545~\text{MeV}\)
2. \(3.045~\text{MeV}\)
3. \(3.5~\text{MeV}\)
4. none of the above
1. \(\lambda_{ph}< \lambda_e\)
2. \(\lambda_{ph}= \lambda_e\)
3. \(\lambda_{ph}>\lambda_e\)
4. \(\lambda_{ph}= 2\lambda_e\)
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