The electron in the hydrogen atom jumps from excited state n=3 to its ground state n=1 and the photons thus emitted irradiate a photosensitive material. If the work function of the material is 5.1 eV, the stopping potential is estimated to be (the energy of the electron in the nth state En=-13.6n2eV)

1. 5.1 V                                               

2. 12.1 V

3. 17.2 V                                             

4. 7 V

Subtopic:  Bohr's Model of Atom |
 64%
From NCERT
NEET - 2010
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A helium-neon laser produces monochromatic light of a wavelength of \(667\) nm. The power emitted is \(9\) mW. The average number of photons arriving per second on average at a target irradiated by this beam is:
1. \(9\times 10^{17}\)
2. \(3\times 10^{16}\)
3. \(9\times 10^{15}\)
4. \(3\times 10^{19}\)

Subtopic:  Particle Nature of Light |
 79%
From NCERT
NEET - 2009
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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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The number of photoelectrons emitted for light of a frequency v (higher than the threshold frequency v0) is proportional to

1. v-v0

2. threshold frequency v0

3. intensity of light

4. frequency of light (v)

Subtopic:  Photoelectric Effect: Experiment |
 77%
From NCERT
NEET - 2009
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The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5V lies in the 

(1) ultraviolet region                               

(2) visible region

(3) infrared region                                   

(4) X-ray region 

Subtopic:  Einstein's Photoelectric Equation |
 57%
From NCERT
NEET - 2008
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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 mass m with an initial velocity v=v0i^ v0>0 is in an electric field E=-E0 i^E0=constant > 0. It's de Broglie wavelength at the time t is given by:

(1) λ01+eE0mtv0

(2) λ01+eE0tmv0

(3) λ0

(4)λ0t.

Subtopic:  De-broglie Wavelength |
 64%
From NCERT
NEET - 2018
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The ratio of momenta of an electron and an \(\alpha \text-\)particle which are accelerated from rest by a potential difference of \(100~\text{V}\) is:
1. \(1\)
2. \(\sqrt{\frac{2m_e}{m_{\alpha}}}\)
3. \(\sqrt{\frac{m_e}{m_{\alpha}}}\)
4. \(\sqrt{\frac{m_e}{2m_{\alpha}}}\)

Subtopic:  Various Atomic Models |
 60%
From NCERT
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The fact that electric charges are integral multiples of the fundamental electronic charge was proved experimentally by 
(1) Planck                   

(2) J.J. Thomson

(3) Einstein                 

(4) Millikan

Subtopic:  Various Atomic Models |
 57%
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 A narrow electron beam passes undeviated through an electric field E = 3×104 volt/m and an overlapping magnetic field B=2×10-3 Weber/m2. If electric field and magnetic field are mutually perpendicular. The speed of the electrons is 
1. \(60\) m/s                       
2. 10.3×107 m/s
3. 1.5×107 m/s             
4. 0.67×10-7 m/s

Subtopic:  Lorentz Force |
 89%
From NCERT
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