The figure shows the variation in photoelectric current (i) with voltage (V) between the electrodes in a photocell for two different radiations. If Ia and Ib are the intensities of the incident radiation and and their respective frequencies, then:
1. | \(I_a>I_b, \nu_b<\nu_a\) | 2. | \(I_a<I_b, \nu_b>\nu_a\) |
3. | \(I_a>I_b, \nu_b=\nu_a\) | 4. | \(I_a<I_b, \nu_b<\nu_a\) |
The work function of a metal surface is 2 eV. When the light of frequency f is incident on the surface, the maximum kinetic energy of the photoelectrons emitted is 5 eV. If the frequency of the incident light is increased to 4f, then the maximum kinetic energy of the photoelectron emitted will be:
1. 20 eV
2. 22 eV
3. 26 eV
4. 28 eV
When a point source of monochromatic light is at a distance of 0.2 m from a photoelectric cell, the cut-off voltage and saturation current are 0.6 volts and 18 mA respectively. What will happen if the same source is placed 0.6 m away from the photoelectric cell?
1. | the stopping potential will be 0.2 volts. |
2. | the stopping potential will be 0.6 volts. |
3. | the saturation current will be 6 mA. |
4. | the saturation current will be 18 mA. |
The de-Broglie wavelength of an electron is the same as that of a photon of wavelength λ. If the mass of an electron is m, then its kinetic energy will be:
1.
2.
3.
4.
The variation of the kinetic energy \((K)\) of photoelectrons as a function of the frequency \((f)\) of the incident radiation is best shown by:
1. | 2. | ||
3. | 4. |
The correct graph between the maximum energy of a photoelectron \(\left(K_{max}\right)\) and the inverse of the wavelength \(\left(\frac{1}{\lambda}\right)\) of the incident radiation is given by the curve:
1. | \(A\) | 2. | \(B\) |
3. | \(C\) | 4. | None of these |
If alpha, beta and gamma rays carry the same momentum, which has the longest wavelength?
1. | Alpha rays | 2. | Beta rays |
3. | Gamma rays | 4. | None, all have same wavelength |
The photoelectric effect is used by a photocell 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. |
A 200 W sodium street lamp emits yellow light of wavelength 0.6 . If it is 25% efficient in converting electrical energy to light, how many photons of yellow light does it emit per second?
1.
2.
3.
4.
In the photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV. What is the corresponding stopping potential?
1. 1.3 V
2. 0.5 V
3. 2.3 V
4. 1.8 V