Work function of a metal is 2.1 eV. Which of the waves of the following wavelengths will be able to emit photoelectrons from its surface ?
(1) 4000 Å, 7500 Å                     

(2) 5500 Å, 6000 Å

(3) 4000 Å, 6000 Å                     

(4) None of these

Subtopic:  Electron Emission |
 52%
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The cathode of a photoelectric cell is changed such that the work function changes from W1 to W2 W2>W1. If the current before and after the change are I1 and I2, all other conditions remaining unchanged, then (assuming >W2) :

(1) I1= I2               

(2) I1I2

(3) I1>I2               

(4) I1<I2<2I1

Subtopic:  Electron Emission |
 63%
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A beam of light of wavelength \(\lambda\) and with illumination \(L\) falls on a clean surface of sodium. If \(N\) photoelectrons are emitted each with kinetic energy \(E\), then:
1. \(N \propto L \) and \(E \propto L \)
2. \(N \propto L \) and \(E \propto \frac{1}{\lambda}\)
3. \(N \propto \lambda\) and \(E \propto L \)
4. \(N \propto \frac{1}{\lambda}\) and \(E \propto \frac{1}{L}\)

Subtopic:  Electron Emission |
 82%
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Which of the following statements is correct

(1) The current in a photocell increases with increasing frequency of light

(2) The photocurrent is proportional to applied voltage

(3) The photocurrent increases with increasing intensity of light

(4) The stopping potential increases with increasing intensity of incident light

Subtopic:  Photoelectric Effect: Experiment |
 87%
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For the intensity \(I\) of a light of wavelength \(5000\) \(\mathring{A}\) the photoelectron saturation current is \(0.40\) μA and the stopping potential is \(1.36\) V, the work function of the metal is:
1. \(2.47\) eV
2. \(1.36\) eV
3. \(1.10\) eV
4. \(0.43\) eV

Subtopic:  Einstein's Photoelectric Equation |
 70%
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The work functions of metals A and B are in the ratio 1 : 2. If light of frequencies f and 2f are incident on the surfaces of A and B respectively, the ratio of the maximum kinetic energies of photoelectrons emitted is (f is greater than threshold frequency of A, 2f is greater than threshold frequency of B) 
(a) 1 : 1               (b) 1 : 2
(c) 1 : 3               (d) 1 : 4

Subtopic:  Einstein's Photoelectric Equation |
 72%
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4 eV is the energy of the incident photon and the work function in 2eV. What is the stopping potential ?

(1) 2V                   

(2) 4V

(3) 6V                   

(4) 22 V 

Subtopic:  Photoelectric Effect: Experiment |
 85%
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The number of photons of wavelength 540 nm emitted per second by an electric bulb of power 100W is (taking h = 6×10-34 J-sec)

(a) 100                 (b) 1000
(c) 3×1020           (d) 3×1018

Subtopic:  Particle Nature of Light |
 78%
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Light of frequency 4v0 is incident on the metal of the threshold frequency v0. The maximum kinetic energy of the emitted photoelectrons is 

(1) 3hv0          

(2) 2hv0

(3) 32hv0         

(4) 12hv0

Subtopic:  Electron Emission | Einstein's Photoelectric Equation |
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Two identical photo-cathodes receive light of frequencies f1 and f2. If the velocities of the photo electrons (of mass m) coming out are respectively v1 and v2, then 
(1) v1-v2=2hmf1-f21/2             

(2) v12-v22=2hmf1-f2

(3) v1+v2=2hmf1+f21/2             

(4) v12+v22=2hmf1+f2

Subtopic:  Einstein's Photoelectric Equation |
 70%
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