An \(\alpha\text-\)particle moves in a circular path of radius \(0.83\) cm in the presence of a magnetic field of \(0.25 ~\text{Wb/m}^2\). The de-Broglie wavelength associated with the particle will be:
1. \(1~\mathring{A}\) 2. \(0.1~\mathring{A}\)
3. \(10~\mathring{A}\) 4. \(0.01~\mathring{A}\)

Subtopic:  De-broglie Wavelength |
 57%
From NCERT
NEET - 2012
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In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by

1. increasing the filament current

2. decreasing the filament current

3. decreasing the potential difference between the anode and filament

4. increasing the potential difference  between the anode and filament

Subtopic:  Davisson & Germer Experiment (OLD NCERT) |
 70%
From NCERT
NEET - 2011
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A radioactive nucleus of mass M emits a photon

of frequency ν and the nucleus recoils. The recoil

energy will be:

(1) h2ν2/2 Mc2

(2) zero

(3) hν

(4) Mc2-

Subtopic:  De-broglie Wavelength |
 51%
From NCERT
NEET - 2011
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In photoelectric emission process from a metal

of work function 1.8 eV, the kinetic energy of most

energetic electrons is 0.5 eV. The corresponding

stopping potential is

(1) 1.2 V

(2) 0.5 V

(3)2.3 V

(4) 1.8 V

Subtopic:  Photoelectric Effect: Experiment |
 77%
From NCERT
NEET - 2011
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Light of two different frequencies whose

photons have energies 1 eV and 2.5 eV

respectively illuminate a metallic surface 

whose function is 0.5 eV successively.

Ratio of maximum speeds of emitted 

electrons will be

(1) 1:2

(2) 1:1

(3) 1:5

(4) 1:4

Subtopic:  Photoelectric Effect: Experiment |
 70%
From NCERT
NEET - 2011
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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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Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 kV then the de-Broglie wavelength associated with the electrons would

1. decrease by 2 times

2. decrease by 4 times

3. increase by 4 times

4. increase by 2 times

Subtopic:  De-broglie Wavelength |
 70%
From NCERT
NEET - 2011
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The threshold frequency for a photo-sensitive metal is 3.3×1014 Hz. If the light of frequency 8.2×1014 Hz 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 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 |
 72%
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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