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 |
 87%
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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 |
 74%
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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 |
 80%
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The work function of metal is 1 eV. Light of wavelength 3000 Å is incident on this metal surface. The velocity of emitted photo-electrons will be
(a) 10 m/sec                           (b) 1×103 m/sec
(c) 1×104 m/sec                     (d) 1×106 m/sec

Subtopic:  Einstein's Photoelectric Equation |
 66%
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The work function of a metal is 1.6×10-19 J. When the metal surface is illuminated by the light of wavelength 6400 Å, then the maximum kinetic energy of emitted photo-electrons will be
(Planck's constant = 6.4×10-34 Js
(a) 14×10-19 J                 (b) 2.8×10-19 J 
(c) 1.4×10-19 J                (d) 1.4×10-19 eV

Subtopic:  Einstein's Photoelectric Equation |
 76%
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Ultraviolet radiations of 6.2 eV falls on an aluminium surface (work function 4.2 eV ). The kinetic energy in joules of the fastest electron emitted is approximately
1. 3.2×10-21             

2. 3.2×10-19

3. 3.2×10-17             

4. 3.2×10-15

Subtopic:  Einstein's Photoelectric Equation |
 91%
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The work function for tungsten and sodium are 4.5 eV and 2.3 eV respectively. If the threshold wavelength λ for sodium is 5460 Å, the value of λ for tungsten is

(1) 5893 Å                   

(2) 10683 Å

(3) 2791 Å                   

(4) 528 Å

Subtopic:  Photoelectric Effect: Experiment |
 70%
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A photon of energy 3.4 eV is incident on a metal having a work function of 2 eV. The maximum K.E. of photo-electrons is equal to:

1. 1.4 eV 2. 1.7 eV
3. 5.4 eV 4. 6.8 eV
Subtopic:  Einstein's Photoelectric Equation |
 91%
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