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The frequency and intensity of a light s...

The frequency and intensity of a light source are both doubled. Consider the following statements
A. The saturation photocurrent remains almost the same
B. The maximum kinetic energy of the photoelectrons is double

A

Both A and B are true

B

A is true but B is false

C

A is false but B is true

D

Both A and B are false

Text Solution

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The correct Answer is:
To analyze the question regarding the effects of doubling the frequency and intensity of a light source on the saturation photocurrent and the maximum kinetic energy of photoelectrons, we can break down the solution step by step. ### Step-by-Step Solution: 1. **Understanding the Photoelectric Effect**: - The photoelectric effect states that when light of sufficient frequency strikes a metal surface, it can eject electrons from that surface. The energy of the incoming photons is given by \( E = h\nu \), where \( h \) is Planck's constant and \( \nu \) is the frequency of the light. 2. **Effect of Doubling Frequency**: - When the frequency of the light is doubled, the energy of each photon also doubles. Thus, if the original frequency is \( \nu \), the new frequency is \( 2\nu \), leading to photon energy \( E' = h(2\nu) = 2h\nu \). 3. **Effect on Saturation Photocurrent**: - The saturation photocurrent is directly related to the number of photoelectrons emitted per second. The number of emitted photoelectrons is proportional to the number of incident photons. - If the intensity of light is doubled, it does not mean that the number of photons emitted per second doubles if the frequency is also doubled. The increase in intensity due to doubling the frequency does not increase the number of photons emitted because the energy per photon has increased. Therefore, the saturation photocurrent remains almost the same. 4. **Effect on Maximum Kinetic Energy**: - The maximum kinetic energy of the emitted photoelectrons can be calculated using Einstein's photoelectric equation: \[ K_{max} = h\nu - \phi \] where \( \phi \) is the work function of the metal. - If the frequency is doubled, the new maximum kinetic energy becomes: \[ K'_{max} = h(2\nu) - \phi = 2h\nu - \phi \] - Comparing the new kinetic energy with the original: \[ K'_{max} = 2(h\nu) - \phi = 2K_{max} + \phi - \phi = 2K_{max} \] - This shows that the maximum kinetic energy is indeed more than double the original kinetic energy, thus the statement that the maximum kinetic energy of the photoelectrons is double is incorrect. 5. **Conclusion**: - Statement A: The saturation photocurrent remains almost the same - **True**. - Statement B: The maximum kinetic energy of the photoelectrons is double - **False**. ### Final Answer: - Statement A is true, and Statement B is false.

To analyze the question regarding the effects of doubling the frequency and intensity of a light source on the saturation photocurrent and the maximum kinetic energy of photoelectrons, we can break down the solution step by step. ### Step-by-Step Solution: 1. **Understanding the Photoelectric Effect**: - The photoelectric effect states that when light of sufficient frequency strikes a metal surface, it can eject electrons from that surface. The energy of the incoming photons is given by \( E = h\nu \), where \( h \) is Planck's constant and \( \nu \) is the frequency of the light. 2. **Effect of Doubling Frequency**: ...
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CP SINGH-PHOTOELECTRIC EFFECT-EXERCISES
  1. Two identical metal plates show photoelectric effect by a light of wav...

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  2. The cathode of a photoelectric cell is changed such that the work func...

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  3. The frequency and intensity of a light source are both doubled. Consid...

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  4. The threshold wavelength for photoelectric emission from a material ...

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  5. A photoelectric cell is illuminated by a point source of light 1 m awa...

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  6. If the distance of 100 Watt lamp is increased from a photocell, the sa...

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  7. A point source causes photoelectric effect from a small metal plate. W...

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  8. When a monochromatic point source of light is at a distance of 0.2 m...

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  9. The collector plate in an experiment on photoelectric effect is kept v...

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  10. The electric field associated with a light wave is given by E= E0 sin...

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  11. A beam of light of wavelength lambda is incident on a metal having wor...

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  12. A photon of energy E ejects a photoelectron from a metel surface whose...

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  13. A monochromatic light of wavelength lambda is incident on an isolated ...

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  14. Photoelectric effect experiments are performed using three different m...

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  15. The graph between 1//lambda and stopping potential (V) of three metals...

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  16. The figure shows a plot of photo current versus anode potential for a ...

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  17. Which of the following is correct regarding de-Broglie wavelength?

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  18. de-Broglie wavelength associated with an electron accelerated through ...

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  19. An electron of mass me and a proton of mass mp are accelerated through...

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