Q. No.The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200 nm falls on it, must be:
1. 2.4 V
2. -1.2 V
3. -2.4 V
4. 1.2 V
2. 3 X 1016
3. 9 x 1015
4. 3 X 1019
| 1. | Curves \(a\) and \(b\) represent incident radiations of different frequencies and different intensities. |
| 2. | Curves \(a\) and \(b\) represent incident radiation of the same frequency but of different intensities. |
| 3. | Curves \(b\) and \(c\) represent incident radiation of different frequencies and different intensities. |
| 4. | Curves \(b\) and \(c\) represent incident radiations of the same frequency having the same intensity. |
1. ultraviolet region.
2. visible region.
3. infrared region.
4. X-ray region.
| 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 particle of mass \(1\) mg has the same wavelength as an electron moving with a velocity of \(3\times 10^{6}\) ms-1. The velocity of the particle is:
(Mass of electron = \(9.1 \times 10^{-31}\) kg)
1. \(2.7 \times 10^{-18}~\text{ms}^{-1}\)
2. \(9 \times 10^{-2}~\text{ms}^{-1}\)
3. \(3 \times 10^{-31}~\text{ms}^{-1}\)
4. \(2.7 \times 10^{-21}~\text{ms}^{-1}\)
A \(5\) W emits monochromatic light of wavelength \(5000~\mathring{A}\). 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. \(2\)
Monochromatic light of frequency 6.0×1014 Hz is produced by a laser. The power emitted is 2×10-3 W. The number of photons emitted, on average, by the source per second is:
1.
2.
3.
4.
A photocell employs a photo-electric effect to convert:
| 1. | change in the frequency of light into a change in electric voltage. |
| 2. | change in the intensity of illumination into a change in photoelectric current. |
| 3. | change in the intensity of illumination into a change in the work function of the photocathode. |
| 4. | change in the frequency of light into a change in the electric current. |
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