A light of wavelength $$\lambda$$ is incident on the metal surface and the ejected fastest electron has speed $$v.$$ If the wavelength is changed to $$\frac{3\lambda}{4},$$ then the speed of the fastest emitted electron will be:

 1 smaller than $$\sqrt{\frac{4}{3}}v$$ 2 greater than $$\sqrt{\frac{4}{3}}$$$$v$$ 3 $$2v$$ 4 zero

Subtopic:  Einstein's Photoelectric Equation |
68%
From NCERT
AIPMT - 1998
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The work function of a metal surface is φ = 1.5 eV. If a light of wavelength 5000 Å falls on it, then the maximum K.E. of the ejected electron will be:

 1 1.2 eV 2 0.98 eV 3 0.45 eV 4 0 eV
Subtopic:  Einstein's Photoelectric Equation |
80%
From NCERT
AIPMT - 1998
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The current conduction in a discharge tube is due to:
1.  electrons only
2.  +ve ions and –ve ions
3.  –ve ions and electrons
4.  +ve ions and electrons

Subtopic:  Photoelectric Effect: Experiment |
From NCERT
AIPMT - 1999
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If a light of amplitude A and wavelength λ is incident on a metallic surface, then the saturation current flow is proportional to (assume cut-off wavelength = ${\lambda }_{0}$):

1. ${A}^{2},$ $if$ $\lambda$ $>$ ${\lambda }_{0}$

2. ${A}^{2},$ $if$ $\lambda$ $<$ ${\lambda }_{0}$

3. $A,$ $if$ $\lambda$ $>$ ${\lambda }_{0}$

4. $A,$ $if$ $\lambda$ $<$ ${\lambda }_{0}$

Subtopic:  Photoelectric Effect: Experiment |
59%
From NCERT
AIPMT - 1999
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Light of wavelength $$3000 ~{\mathring{\mathrm{A}}}$$ in Photoelectric effect gives electron of maximum kinetic energy $$0.5 ~\text{eV}$$. If the wavelength changes to $$2000 ~{\mathring{\mathrm{A}}}$$ then the maximum kinetic energy of emitted electrons will be:

 1 less than $$0.5 ~\text{eV}$$ 2 $$0.5 ~\text{eV}$$ 3 greater than $$0.5 ~\text{eV}$$ 4 the photoelectric effect does not occur

Subtopic:  Einstein's Photoelectric Equation |
82%
From NCERT
AIPMT - 1999
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If the K.E. of an electron and a photon is the same, then the relation between their de-Broglie wavelength will be:

1. ${\lambda }_{ph}$ $<$ ${\lambda }_{e}$

2. ${\lambda }_{ph}$ $=$ ${\lambda }_{e}$

3. ${\lambda }_{ph}$ $>$ ${\lambda }_{e}$

4. ${\lambda }_{ph}$ $=2$ ${\lambda }_{e}$

Subtopic:  De-broglie Wavelength |
52%
From NCERT
AIPMT - 1999
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The total energy of an electron is $$3.555~\text{MeV}$$. Its kinetic energy will be:
1.  $$3.545~\text{MeV}$$
2.  $$3.045~\text{MeV}$$
3.  $$3.5~\text{MeV}$$
4.  none of the above

Subtopic:  Electron Emission |
From NCERT
AIPMT - 1999
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What did Einstein prove by the photo-electric effect?

1. E = h$$\nu$$

2. $KE=\frac{1}{2}m{v}^{2}$

3. $E=m{c}^{2}$

4. $E=\frac{-Rh{c}^{2}}{{n}^{2}}$

Subtopic:  Einstein's Photoelectric Equation |
60%
From NCERT
AIPMT - 2000
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Which one among the following shows the particle nature of light?
1. Photoelectric effect
2. Interference
3. Refraction
4. Polarisation

Subtopic:  Particle Nature of Light |
90%
From NCERT
AIPMT - 2001
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A photo-cell is illuminated by a source of light, which is placed at a distance $$d$$ from the cell. If the distance becomes $$\frac{d}{2}$$, then the number of electrons emitted per second will be:
1. same
2. four times
3. two times
4. one-fourth

Subtopic:  Photoelectric Effect: Experiment |
71%
From NCERT
AIPMT - 2001
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