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The Work Function of a Metal is Hv0. Light of Frequency V Falls on this Metal. Photoelectric Effect Will Take Place Only If

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प्रश्न

The work function of a metal is hv0. Light of frequency v falls on this metal. Photoelectric effect will take place only if

पर्याय

  • v ≥ v0

  • v > 2v0

  • v < v0

  • v < v0/2

MCQ
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उत्तर

v ≥ v0

As the work function of the metal is hv0, the threshold frequency of the metal is v0.

For photoelectric effect to occur, the frequency of the incident light should be greater than or equal to the threshlod frequency of the metal on which light is incident.

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  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 42: Photoelectric Effect and Wave-Particle Duality - MCQ [पृष्ठ ३६३]

APPEARS IN

एचसी वर्मा Concepts of Physics Volume 1 and 2 [English]
पाठ 42 Photoelectric Effect and Wave-Particle Duality
MCQ | Q 6 | पृष्ठ ३६३

संबंधित प्रश्‍न

What is the speed of a photon with respect to another photon if (a) the two photons are going in the same direction and (b) they are going in opposite directions?


Should the energy of a photon be called its kinetic energy or its internal energy?


If the frequency of light in a photoelectric experiment is doubled, the stopping potential will ______.


If the wavelength of light in an experiment on photoelectric effect is doubled,
(a) photoelectric emission will not take place
(b) photoelectric emission may or may not take place
(c) the stopping potential will increase
(d) the stopping potential will decrease


Calculate the momentum of a photon of light of wavelength 500 nm.

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


An atom absorbs a photon of wavelength 500 nm and emits another photon of wavelength 700 nm. Find the net energy absorbed by the atom in the process.

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


When the sun is directly overhead, the surface of the earth receives 1.4 × 103 W m−2 of sunlight. Assume that the light is monochromatic with average wavelength 500 nm and that no light is absorbed in between the sun and the earth's surface. The distance between the sun and the earth is 1.5 × 1011 m. (a) Calculate the number of photons falling per second on each square metre of earth's surface directly below the sun. (b) How many photons are there in each cubic metre near the earth's surface at any instant? (c) How many photons does the sun emit per second?

(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)


Find the maximum kinetic energy of the photoelectrons ejected when light of wavelength 350 nm is incident on a cesium surface. Work function of cesium = 1.9 eV

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


The electric field associated with a monochromatic beam is 1.2 × 1015 times per second. Find the maximum kinetic energy of the photoelectrons when this light falls on a metal surface whose work function is 2.0 eV.

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


Define the term: threshold frequency


Define the term: stopping potential in the photoelectric effect.


In photoelectric effect, the photoelectric current started to flow. This means that the frequency of incident radiations is ______.


Do all the electrons that absorb a photon come out as photoelectrons?


Two monochromatic beams A and B of equal intensity I, hit a screen. The number of photons hitting the screen by beam A is twice that by beam B. Then what inference can you make about their frequencies?


The graph shows the variation of photocurrent for a photosensitive metal

  1. What does X and A on the horizontal axis represent?
  2. Draw this graph for three different values of frequencies of incident radiation ʋ1, ʋ2 and ʋ33 > ʋ2 > ʋ1) for the same intensity.
  3. Draw this graph for three different values of intensities of incident radiation I1, I2 and I3 (I3 > I2 > I1) having the same frequency.

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.


  • 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.

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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