Photoelectric Effects and deBroglie Equation – Page 2 – Rankers Physics
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Photoelectric Effects and deBroglie Equation

Question 1:

Energy from the sun is received on the earth at the rate of 2 cal per cm² per min. If average
wavelength of solar light be taken at 5500 Å, then how many photons are received on the earth per cm² per min ?

\[\left( h=6.6\times 10^{-34}J-s,cal = 4.2 J \right)\]

\[1.5\times 10^{13}\]
\[2.9\times 10^{13}\]
\[2.3\times 10^{19}\]
\[1.75\times 10^{19}\]
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No solution provided for this question.

Question 2:

Monochromatic light of frequency f1 is incident on a photocell and the stopping potential is found to be V1. What is the new stopping potential of the cell if it is radiated by monochromatic light of frequency f2?

\[V_{1}-\frac{h}{e}\left( f_{2}-f_{1} \right)\]
\[V_{1}+\frac{h}{e}\left( f_{2}+f_{1} \right)\]
\[V_{1}-\frac{h}{e}\left( f_{2}+f_{1} \right)\]
\[V_{1}+\frac{h}{e}\left( f_{2}-f_{1} \right)\]
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No solution provided for this question.

Question 3:

The correct graph between the maximum energy of a photoelectron and the inverse of
wavelenght of the incident radiation is given by the curve

A
B
C
None of the above
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No solution provided for this question.

Question 4:

A photon and an electron have equal energy E. \[\lambda_{photon}/\lambda_{electron}\]
is proportional to

√E
1/√E
1/E
Does not depend upon E
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No solution provided for this question.

Question 5:

Ultraviolet light of wavelength 300 nm and intensity 1.0 watt/m² falls on the surface of a
photosensitive material. If 1% of the incident photons produce photoelectrons, then the
numer of phtoelectrons emitted from an area of 1.0 cm² of the surface is nearly

\[9.61\times 10^{14}per sec\]
\[4.12\times 10^{13}per sec\]
\[1.51\times 10^{12}per sec\]
\[2.13\times 10^{11}per sec\]
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No solution provided for this question.

Question 6:

A photon of wavelength 6630 Å is incident on a totally reflecting surface. The momentum
delivered by the photon is equal to

\[6.63\times 10^{-27}kg-m/sec\]
\[2\times 10^{-27}kg-m/sec\]
\[10^{-27}kg-m/sec\]
\[3\times 10^{-27}kg-m/sec\]
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No solution provided for this question.

Question 7:

Photoelectric emission is observed from a metallic surface for frequencies ν1 and ν2 of the incident light rays (ν1 > ν2). If the maximum value of kinetic energy of the photoelectrons emitted in the two cases are in the ratio of 1 : k, then the threshold frequency of the metallic surface is :-

\[\frac{\nu_{1}-\nu_{2}}{k-1}\]
\[\frac{k\nu_{1}-\nu_{2}}{k-1}\]
\[\frac{k\nu_{2}-\nu_{1}}{k-1}\]
\[\frac{\nu_{2}-\nu_{1}}{k}\]
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No solution provided for this question.

Question 8:

The ratio of de-Broglie wavelengths of molecules of hydrogen and helium which are at temperature 27°C and 127° respectively is :-

1/2
\[\sqrt{\frac{3}{8}}\]
\[\sqrt{\frac{8}{3}}\]
1
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No solution provided for this question.

Question 9:

The figure shows the variation of photo current with anode potential for a photo-sensitive surface for three different radiations. Let Ia, Ib, and Ic be the intensities and fa, fb and fc be the frequencies for the curves a, b and c respectively :-

\[f_{a}=f_{b} and I_{a}\neq I_{b}\]
\[f_{a}=f_{c} and I_{a}= I_{c}\]
\[f_{a}=f_{b} and I_{a}= I_{b}\]
\[f_{b}=f_{c} and I_{b}= I_{c}\]
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No solution provided for this question.

Question 10:

The anode voltage of a photocell is kept fixed. The wavelength λ of the light falling on the
cathode is gradually changed. The plate current I of the photocell varies as given below :-

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No solution provided for this question.