The threshold wavelength for photoelectric emission from a material is 5200 Å. Photo-electrons will be emitted when this material is illuminated with monochromatic radiation from :

(1) 50-watt infrared lamp

(2) 50-watt ultraviolet lamp

(3) 1-watt ultraviolet lamp

(4) Both (2) and (3)

Subtopic:  Electron Emission |
 60%
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Threshold frequency for a metal is 1015 Hz. Light of λ=4000 A0 falls on its surface. Which of the following statements is correct

(1) No photoelectric emission takes place

(2) Photo-electrons come out with zero speed

(3) Photo-electrons come out with 103 m/sec speed

(4) Photo-electrons come out with 105 m/sec speed

Subtopic:  Electron Emission |
 70%
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Einstein got Nobel prize on which of the following works

(1) Mass-energy relation

(2) Special theory of relativity

(3) Photoelectric equation

(4) (a) and (b) both

Subtopic:  Einstein's Photoelectric Equation |
 61%
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The photo-electrons emitted from a surface of sodium metal are such that 

(1) They all are of the same frequency

(2) They have the same kinetic energy

(3) They have the same de Broglie wavelength

(4) They have their speeds varying from zero to a certain maximum

Subtopic:  Electron Emission |
 64%
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A metal surface of work function \(1.07\) eV is irradiated with light of wavelength \(332\) nm. The retarding potential required to stop the escape of photo-electrons is:
1. \(4.81\) eV
2. \(3.74\) eV
3. \(2.66\) eV
4. \(1.07\) eV
 

Subtopic:  Einstein's Photoelectric Equation |
 71%
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In a photo cell, the photo-electrons emission takes place
(1) After 10-1 sec on incident of light rays

(2) After 10-3 sec on incident of light rays

(3) After 10-6 sec on incident of light rays

(4) After 10-8 sec on incident of light rays

Subtopic:  Electron Emission |
 61%
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When light falls on a metal surface, the maximum kinetic energy of the emitted photo-electrons depends upon

(1) The time for which light falls on the metal

(2) Frequency of the incident light

(3) Intensity of the incident light

(4) Velocity of the incident light

Subtopic:  Einstein's Photoelectric Equation |
 85%
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The electrons are emitted in the photoelectric effect from a metal surface 

(1) Only if the frequency of the incident radiation is above a certain threshold value

(2) Only if the temperature of the surface is high

(3) At a rate that is independent of the nature of the metal

(4) With a maximum velocity proportional to the frequency of the incident radiation

Subtopic:  Photoelectric Effect: Experiment |
 86%
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The work function of a metal is \(4.2 ~\text{eV}\), its threshold wavelength will be:
1. \(4000~\mathring{\text{A}}\)                   
2. \(3500~\mathring{\text{A}}\)
3. \(2955~\mathring{\text{A}}\) 
4. \(2500~\mathring{\text{A}}\)

Subtopic:  Photoelectric Effect: Experiment |
 73%
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The number of photo-electrons emitted per second from a metal surface increases when:

1. The energy of incident photons increases. 2. The frequency of incident light increases.
3. The wavelength of the incident light increases. 4. The intensity of the incident light increases.
Subtopic:  Photoelectric Effect: Experiment |
 81%
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