मराठी

Assertion (A): For the radiation of a frequency greater than the threshold frequency, the photoelectric current is proportional to the intensity of the radiation.

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प्रश्न

  • Assertion (A): For the radiation of a frequency greater than the threshold frequency, the photoelectric current is proportional to the intensity of the radiation.
  • Reason (R): Greater the number of energy quanta available, the greater the number of electrons absorbing the energy quanta and the greater the number of electrons coming out of the metal.

पर्याय

  • If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

  • If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

  • If Assertion is true but Reason is false.

  • If both Assertion and Reason are false.

MCQ
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उत्तर

If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation:

When the frequency of the incident radiation exceeds the threshold frequency, the photoelectric current is proportional to the intensity of the radiation. As a result, the assertion is correct. As the intensity rises, so does the number of energy quanta accessible. By absorbing more energy quanta, a bigger number of electrons are emitted. A higher number of electrons equals a higher current. As a result, the photoelectric current becomes proportional to radiation intensity. So, the reason is also true, and it adequately explains the assumption.

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2023-2024 (March) Board Sample Paper

संबंधित प्रश्‍न

Monochromatic radiation of wavelength 640.2 nm (1 nm = 10−9 m) from a neon lamp irradiates photosensitive material made of caesium on tungsten. The stopping voltage is measured to be 0.54 V. The source is replaced by an iron source and its 427.2 nm line irradiates the same photo-cell. Predict the new stopping voltage.


A parallel beam of monochromatic light of wavelength 663 nm is incident on a totally reflecting plane mirror. The angle of incidence is 60° and the number of photons striking the mirror per second is 1.0 × 1019. Calculate the force exerted by the light beam on the mirror.

(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)


A beam of white light is incident normally on a plane surface absorbing 70% of the light and reflecting the rest. If the incident beam carries 10 W of power, find the force exerted by it on the surface.

(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)


A sphere of radius 1.00 cm is placed in the path of a parallel beam of light of large aperture. The intensity of the light is 0.5 W cm−2. If the sphere completely absorbs the radiation falling on it, Show that the force on the sphere due to the light falling on it is the same even if the sphere is not perfectly absorbing.


On the basis of the graphs shown in the figure, answer the following questions :

(a) Which physical parameter is kept constant for the three curves?

(b) Which is the highest frequency among v1, v2, and v3?


Why it is the frequency and not the intensity of the light source that determines whether the emission of photoelectrons will occur or not? Explain.


Read the following paragraph and answer the questions.

The figure shows the variation of photoelectric current measured in a photocell circuit as a function of the potential difference between the plates of the photocell when light beams A, B, C and D of different wavelengths are incident on the photocell. Examine the given figure and answer the following questions:

  1. Which light beam has the highest frequency and why?
  2. Which light beam has the longest wavelength and why?
  3. Which light beam ejects photoelectrons with maximum momentum and why?

The figure shows a plot of stopping potential (V0) versus `1/lambda`, where λ is the wavelength of the radiation causing photoelectric emission from a surface. The slope of the line is equal to ______.


What is the effect of threshold frequency and stopping potential on increasing the frequency of the incident beam of light? Justify your answer.


The difference between threshold wavelengths for two metal surfaces A and B having work function ΦA = 9 eV and  ΦB = 4.5 eV in nm is ______.

(Given, hc = 1242 eV nm)


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