Photons of wavelength \(\lambda\) cause the emission of photoelectrons from a metallic surface, the de-Broglie wavelength of the fastest photoelectron being \(\lambda_d\). A graph of \(\dfrac{1}{\lambda} \text { vs } \dfrac{1}{\lambda_{d}}\) is:
1. a straight line passing through the origin.
2. a circle.
3. an ellipse.
4. a parabola.

Subtopic:  De-broglie Wavelength |
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The electric field associated with a light wave is given by \(E = E_0~ (\sin \omega_1 t)~ (\sin \omega_2 t)\).
This light wave falls on a metal having a threshold frequency, \(\nu_0.\) The maximum kinetic energy of the emitted photoelectrons will be: (\(h\) is Planck's constant)
1. Either \(\dfrac{h \omega_{1}}{2 \pi}\) or \(\dfrac{h \omega_{2}}{2 \pi}\)
2. Either \(\left(\dfrac{h \omega_{1}}{2 \pi}-h \nu_{0}\right)\) or \(\left(\dfrac{h \omega}{2 \pi}-h \nu_{0}\right)\)
3.  \(\dfrac{h\left(\omega_{1}+\omega_{2}\right)}{2 \pi}-h \nu_{0}\)
4. Both \(\dfrac{h\left(\omega_{1}+\omega_{2}\right)}{2 \pi}-h \nu_{0}\) and \(\dfrac{h\left |\omega_{1}-\omega_{2}\right|}{2 \pi}-h \nu_{0}\)
Subtopic:  Einstein's Photoelectric Equation |
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Photons of frequency \(\nu\) fill a room. A metallic plate having a work function \(W\) \((<h\nu)\) is moved with a velocity \(v\), in this room. The maximum energy of the emitted photoelectrons: (in the plate's frame) 
1. does not depend on \(v\) 
2. increases as \(v\) increases 
3. decreases as \(v\) increases 
4. first increases and then decreases as \(v\) is increased 
Subtopic:  Einstein's Photoelectric Equation |
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The frequency of light in a photoelectric experiment is tripled. The stopping potential will:
1. be tripled 2. be more than tripled
3. be less than tripled 4. become one-third
Subtopic:  Photoelectric Effect: Experiment |
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Photons of light of wavelength, \(\lambda=400\) nm are incident on a composite photocathode consisting of multiple regions with metals having work functions of \(2.1\) eV and \(1.1\) eV. The emitted photoelectrons are sent through a retarding potential difference, \(V_0\). What is the minimum value of \(V_0\) required to stop all electrons? (take: \(hc=1240\) eV-nm)
1. \(1\) V 2. \(1.5\) V
3. \(2\) V 4. \(5.2\) V
Subtopic:  Einstein's Photoelectric Equation |
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A metallic ball (work function: \(2\) eV) is irradiated with light consisting of photons of wavelength \(200\) nm. The ball has an initial charge, giving it a potential \(1\) V. Take the product of Planck's constant and velocity of light, hc as \(1240\) eV-nm. The final potential of the ball, when photoemission practically stops, is: 
1. \(2\)
2. \(3.2\)
3. \(4.2\)
4. \(5.2\) V
Subtopic:  Photoelectric Effect: Experiment |
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Photoelectrons emerging from a photocathode (work function: \(2.2~\text{eV}\)) are allowed to fall onto a gas containing hydrogen atoms in the ground state and the first excited state. What is the minimum energy of the photons incident on the photo-cathode that will cause the photoelectrons to transfer energy to the \(\mathrm{H\text-}\)atoms?
1. \(13.6~\text{eV}+2.2~\text{eV}\)
2. \((10.2+2.2)~\text{eV}\)
3. \((3.4+2.2)~\text{eV}\)
4. \((1.89+2.2)~\text{eV}\)
Subtopic:  Photoelectric Effect: Experiment |
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A fraction \(f\) of the incident energy in a beam of light of wavelength \(\lambda\) is absorbed by a metallic surface and causes photoemission. If the power of the beam falling on the surface is \(P\), then the maximum photocurrent is:
(\(e\) is electronic charge, \(h\) is Planck's constant, \(c\) is the velocity of light in vacuum)
1. \(\dfrac{\lambda{P}}{h c} f\) 2. \(\dfrac{2\lambda{P}}{h c} f\)
3. \(\dfrac{\lambda{P}}{h c} f e\) 4. \(\dfrac{2\lambda{P}}{h c} f e\)
Subtopic:  Photoelectric Effect: Experiment |
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\(A\) and \(B\) are two metals with threshold frequencies \(1.8\times 10^{14}\ \) Hz and \(2.2\times 10^{14}\ \) Hz. Two identical photons of energy \(0.825\) eV each are incident on them. Then, photoelectrons are emitted in:
(Take \(h=6.6\times 10^{-34}\ \) J-s)
1. \(B\) only
2. \(A\) only
3. neither \(A\) nor \(B\)
4. both \(A\) and \(B\)
Subtopic:  Photoelectric Effect: Experiment |
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A photon of energy \(10.2\) eV corresponds to light of wavelength \(\lambda_0\). Due to electron transition from \(n = 2 \) to \(n = 1\) in a hydrogen atom, light of wavelength \(\lambda\) is emitted. If we take into account the recoil of atom when photon is emitted then: 
 
1. \(\lambda = \lambda_0\)
2. \(\lambda < \lambda_0\)
3. \(\lambda > \lambda_0\)
4. data is not sufficient to reach a conclusion 
Subtopic:  Photoelectric Effect: Experiment |
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