Q. No.For photoelectric emission from certain metal, the cut-off frequency is . If radiation of frequency 2 impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)
1.
2.
3.
4. none of these
1.
2.
Photoelectric emission occurs only when the incident light has more than a certain minimum
1. wavelength
2. intensity
3. frequency
4. power
Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 kV then the de-Broglie wavelength associated with the electrons would
1. decrease by 2 times
2. decrease by 4 times
3. increase by 4 times
4. increase by 2 times
The threshold frequency for a photo-sensitive metal is If the light of frequency is incident on this metal, the cut-off voltage for the photo-electric emission is nearly:
1. 2 V 2. 3 V
3. 5 V 4. 1 V
A source S1 is producing, 1015 photons/s of wavelength 5000 . Another source S2 is producing 1.02 1015 photons per second of wavelength 5100 . Then, (power of S2)/(power of S1) is equal to
1. 1.00 2. 1.02
3. 1.04 4. 0.98
| 1. | \(2.4\) V | 2. | \(-1.2\) V |
| 3. | \(-2.4\) V | 4. | \(1.2\) V |
| 1. | \(N\) and \(2T\) | 2. | \(2N\) and \(T\) |
| 3. | \(2N\) and \(2T\) | 4. | \(N\) and \(T\) |
The electron in the hydrogen atom jumps from excited state to its ground state and the photons thus emitted irradiate a photosensitive material. If the work function of the material is the stopping potential is estimated to be (the energy of the electron in the nth state )
1.
2.
3.
4.
1. \(9\times 10^{17}\)
2. \(3\times 10^{16}\)
3. \(9\times 10^{15}\)
4. \(3\times 10^{19}\)
The number of photoelectrons emitted for light of a frequency v (higher than the threshold frequency ) is proportional to
1.
2. threshold frequency
3. intensity of light
4. frequency of light (v)
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