The energy of a hydrogen atom in the ground state is \(-13.6~\text{eV}\). What is the energy of a \(\mathrm{He}^+\) ion in the first excited state?
1. \(-13.6~\text{eV}\)
2. \(-27.2~\text{eV}\)
3. \(-54.4~\text{eV}\)
4. \(-6.8~\text{eV}\)

Subtopic:  Bohr's Model of Atom |
 73%
From NCERT
NEET - 2010
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A source Sis producing, 1015 photons/s of wavelength 5000 A. Another source S2 is producing 1.02× 1015 photons per second of wavelength 5100 A. Then, (power of S2)/(power of S1) is equal to

1. 1.00                 2. 1.02

3. 1.04                 4. 0.98

Subtopic:  Photoelectric Effect: Experiment |
 73%
From NCERT
NEET - 2010
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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 |
 58%
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 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 \(667~\text{nm}.\) The power emitted is \(9~\text{mW}.\) 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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