A photo-cell is illuminated by a source of light, which is placed at a distance \(d\) from the cell. If the distance becomes \(\frac{d}{2}\), then the number of electrons emitted per second will be:
1. same
2. four times
3. two times
4. one-fourth
A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then:
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 |
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 one among the following shows 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. \(\alpha-\)particle
3. neutron
4. \(\beta-\)particle
The value of Planck's constant is:
1.
2.
3.
4.
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
If the K.E. of an electron and a photon is the same, then the relation between their de-Broglie wavelength will be:
1.
2.
3.
4.