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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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The photoelectric threshold wavelength for a metal surface is 6600 Å. The work function for this is 
(1) 1.87 V                             

(2) 1.87 eV

(3) 18.7 eV                             

(4) 0.18 eV

Subtopic:  Photoelectric Effect: Experiment |
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Photoelectric effect was successfully explained first by
(1) Planck               

(2) Hallwash

(3) Hertz                 

(4) Einstein

Subtopic:  Photoelectric Effect: Experiment |
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A photocell is receiving light from a source placed at a distance of 1 m. If the same source is placed at a distance of 2 m, then the ejected electron:

1. moves with one-fourth of energy as that of the initial energy.
2. moves with one-fourth of momentum as that of the initial momentum.
3. will be half in number.
4. will be one-fourth in number.
Subtopic:  Electron Emission |
 65%
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