# Photoelectric emission occurs only when the incident light has more than a certain minimum  1. wavelength 2. intensity 3. frequency 4. power

Subtopic:  Photoelectric Effect: Experiment |
78%
From NCERT
NEET - 2011
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The threshold frequency for a photo-sensitive metal is  If the light of frequency  is incident on this metal, the cut-off voltage for the photo-electric emission is nearly:

1. 2 V                                        2. 3 V

3. 5 V                                         4. 1 V

Subtopic:  Photoelectric Effect: Experiment |
63%
From NCERT
NEET - 2011
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The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface having a work function of $$5.01$$ eV when ultraviolet light of $$200$$ nm falls on it is:
 1 $$2.4$$ V 2 $$-1.2$$ V 3 $$-2.4$$ V 4 $$1.2$$ V
Subtopic:  Einstein's Photoelectric Equation |
57%
From NCERT
NEET - 2010
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When monochromatic radiation of intensity $$I$$ falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are $$N$$ and $$T$$ respectively. If the intensity of radiation is $$2I$$ what is the number of emitted electrons and their maximum kinetic energy?
 1 $$N$$ and $$2T$$ 2 $$2N$$ and $$T$$ 3 $$2N$$ and $$2T$$ 4 $$N$$ and $$T$$
Subtopic:  Photoelectric Effect: Experiment |
82%
From NCERT
NEET - 2010
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The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three difference radiations. Which one of the following is a correct statement?

(1) Curves a and b represent incident radiations of different frequencies and different intensities

(2) Curves a and b represent incident radiations of same frequency but of different intensities

(3) Curves b and c represent incident radiations of different frequencies and different intensities

(4) Curves b and c represent incident radiations of same frequency having same intensity

Subtopic:  Photoelectric Effect: Experiment |
83%
From NCERT
NEET - 2009
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A particle of mass $$1$$ mg has the same wavelength as an electron moving with a velocity of $$3\times 10^{6}~\text{m/s}$$. What will be the velocity of the particle? (mass of electrons = $$9.1\times 10^{-31}$$ kg )
 1 $$2.7 \times 10^{-18} ~\text{ms}^{-1}$$ 2 $$9 \times 10^{-2} ~\text{ms}^{-1}$$ 3 $$3 \times 10^{-31}~\text{ms}^{-1}$$ 4 $$2.7 \times 10^{-21} ~\text{ms}^{-1}$$
Subtopic:  De-broglie Wavelength |
51%
From NCERT
NEET - 2008
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An electron  with an initial velocity v= is in an electric field E It's de Broglie wavelength at the time $t$ is given by:

(1) $\frac{{\lambda }_{0}}{\left(1+\frac{e{E}_{0}}{m}\frac{t}{{v}_{0}}\right)}$

(2) ${\lambda }_{0}\left(1+\frac{e{E}_{0}t}{m{v}_{0}}\right)$

(3) ${\lambda }_{0}$

(4)${\lambda }_{0}t.$

Subtopic:  De-broglie Wavelength |
64%
From NCERT
NEET - 2018
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Cathode rays are similar to visible light rays in that

(1) They both can be deflected by electric and magnetic fields

(2) They both have a definite magnitude of wavelength

(3) They both can ionize a gas through which they pass

(4) They both can expose a photographic plate

Subtopic:  Photoelectric Effect: Experiment |
From NCERT
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Electron volt is a unit of
(1) Potential

(2) Charge

(3) Power

(4) Energy

Subtopic:  Electron Emission |
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In an electron gun, the electrons are accelerated by the potential V. If e is the charge and m is the mass of an electron, then the maximum velocity of these electrons will be

(1) $\frac{2\mathrm{eV}}{\mathrm{m}}$

(2) $\sqrt{\frac{2\mathrm{eV}}{\mathrm{m}}}$

(3) $\sqrt{\frac{2\mathrm{m}}{\mathrm{eV}}}$

(4) $\frac{{\mathrm{V}}^{2}}{2\mathrm{em}}$

Subtopic:  Electron Emission |
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