Assertion (A): An electron microscope is based on de Broglie’s hypothesis of matter waves.
Reason (R): Higher the accelerating potential, smaller is the de Broglie wavelength of the electron.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
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Assertion (A) is true: Electron microscopes utilize the wave nature of electrons. Reason (R) is true: de Broglie wavelength \(\lambda = h/\sqrt{2meV}\) decreases with higher potential (V). R explains A, as smaller wavelength allows better resolution.
Assertion (A): Increase in intensity of light increases the kinetic energy of photoelectrons.
Reason (R): At stopping potential, no current flows in the circuit.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
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Assertion (A) is false: Kinetic energy of photoelectrons depends on frequency, not intensity. Reason (R) is true: Stopping potential is the reverse potential that stops all photocurrent. As (A) is false, option (4) is chosen by elimination.
Assertion (A): Work function of a metal increases with increase in intensity of incident light.
Reason (R): Maximum kinetic energy of ejected photoelectrons depends upon the intensity of incident light.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
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Assertion (A) is false: Work function is a characteristic property of the metal and is independent of light intensity.
Reason (R) is false: Maximum kinetic energy depends on frequency, not intensity. Both statements are false.
Assertion (A): In the process of photo electric emission, all the emitted photoelectrons have same KE.
Reason (R): According to Einstein’s photo electric equation \(KE= h\nu – \phi\).
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
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Assertion (A) is false: Kinetic energy of emitted photoelectrons varies from zero to maximum. Reason (R) is false: Einstein's equation is \(KE_{max}= h\nu - \phi\). Both statements are false.
Assertion (A): In photo electric effect, photo electrons come out from inner orbits of atom.
Reason (R): Free electrons of the metal can not absorb energy of a photon.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
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Assertion (A) is false: Photoelectrons are ejected from the surface of the metal, not inner orbits. Reason (R) is false: Free electrons absorb photon energy to be ejected. Both statements are false.
Assertion (A): Kinetic energy of photoelectrons emitted by a photosensitive surface depends upon the intensity of incident photon.
Reason (R): The ejection of electrons from metallic surface is possible with frequency of incident photon below the threshold frequency.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
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Kinetic energy of photoelectrons depends on the frequency of incident light, not its intensity. Photoelectric emission requires the incident photon's frequency to be above the threshold frequency \(\nu_0\). Thus, both assertion (A) and reason (R) are false.
Assertion (A): Photoelectrons have a range of kinetic energy.
Reason (R): The work function varies as a function of depth from the surface.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
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Photoelectrons exhibit a range of kinetic energies because electrons lose varying amounts of energy while escaping the material. The work function (\phi\) is a constant for a given surface and does not vary with depth. Thus, assertion (A) is true, but reason (R) is false.
Assertion (A): Photoelectric effect demonstrates the wave nature of light.
Reason (R): The number of photoelectrons is proportional to the frequency of light.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
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The photoelectric effect experimentally supports the particle (photon) nature of light, not its wave nature. The number of photoelectrons emitted is directly proportional to the intensity of incident light, not its frequency. Therefore, both assertion (A) and reason (R) are false.
Assertion (A): On increasing the frequency of incident light, the photoelectric current increases.
Reason (R): Photoelectric current depends upon the wavelength of incident light.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
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Increasing the frequency of incident light increases the kinetic energy of emitted photoelectrons, not the photoelectric current. Photoelectric current depends primarily on the intensity of the incident light, provided the frequency is above the threshold. Therefore, both assertion (A) and reason (R) are false.
Assertion (A): In photoelectric effect, the number of photoelectrons emitted is always equal to number of photons incident.
Reason (R): All the photons falling on the surface will eject photoelectrons.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
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The number of emitted photoelectrons is generally less than the number of incident photons due to quantum efficiency and reflection losses. Photons can only eject electrons if their energy \(\text{h}\nu\) exceeds the work function \(\phi\). Both assertion (A) and reason (R) are false.