- 1(current)
Q. No.Two radiations of photons energies \(1\) eV and \(2.5\) eV, successively illuminate a photosensitive metallic surface of work function \(0.5\) eV. The ratio of the maximum speeds of the emitted electrons is:
1. \(1:2\)
2. \(1:1\)
3. \(1:5\)
4. \(1:4\)
When monochromatic radiation of intensity I falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are N and T respectively. If the intensity of radiation is 2I, the number of emitted electrons and their maximum kinetic energy are respectively:
1. 2N and T
2. 2N and 2T
3. N and T
4. N and 2T
| 1. | excitation of electrons in the atoms |
| 2. | a collision between the atoms of the gas |
| 3. | collisions between the charged particles emitted from the cathode and the atoms of the gas |
| 4. | a collision between different electrons of the atoms of the gas |
A 5 W emits monochromatic light of wavelength 5000 Å. When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved 1.0 m away, the number of photoelectrons liberated is reduced by a factor of?
1. 4
2. 8
3.16
4. 2
J.J. Thomson's cathode-ray tube experiment
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 e/m of electrons is much greater than the e/m of protons |
| 4. | the e/m ratio of the cathode ray particles changes when a different gas is placed in the discharge tube |
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. |
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(current)
Q. No.
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