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Dual Nature of Radiation and Matter · Question 32

AIPMT 2015MCQMedium📈 Topic in 50% papers+4−1
1

Light of wavelength 500 nm is incident on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is

  1. 2.8 10-9 m
  2. 2.8 10-12 m
  3. < 2.8 10-10 m
  4. < 2.8 10-9 m

Answer

(1) 2.8 10-9 m

Solution

Energy of the photon: E = hc = 1240 eV nm500 nm = 2.48 eV

Maximum kinetic energy: K = E - 0 = 2.48 - 2.28 = 0.20 eV

= 0.20 1.6 10-19 = 3.2 10-20 J

Minimum de Broglie wavelength: = h 2mK

= 6.63 10-34 2 9.1 10-31 3.2 10-20

= 6.63 10-342.41 10-25 2.8 10-9 m

The emitted electrons have kinetic energies from 0 up to K , their wavelengths are

2.8 10-9 m

Answer: (1)

AIPMT 2015

Keep practising — Dual Nature of Radiation and Matter

2

Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2015 (Cancelled)
3

A certain metallic surface is illuminated with monochromatic light of wavelength, . The stopping potential for photo-electric current for this light is 3V0. If the same surface is illuminated with light of wavelength 2 , the stopping potential is V0. The threshold wavelength for this surface for photo-electric effect is

  1. 4
  2. 6
  3. 6
  4. 4
AIPMT 2015 (Cancelled)
4

When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is

  1. 0.65 eV
  2. 1.0 eV
  3. 1.3 eV
  4. 1.5 eV
AIPMT 2014
5

If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de Broglie wavelength of the particle is

  1. 25
  2. 75
  3. 60
  4. 50
AIPMT 2014
6

A parallel beam of fast moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct ?

  1. The angular width of the central maximum will decrease.
  2. The angular width of the central maximum will be unaffected.
  3. Diffraction pattern is not observed on the screen in the case of electrons.
  4. The angular width of the central maximum of the diffraction pattern will increase.
NEET 2013
7

The wavelength e of an electron and p of a photon of same energy E are related by

  1. p e
  2. p 1 e
  3. p e2
  4. p e
NEET 2013
8

For photoelectric emission from certain metal the cutoff frequency is . If radiation of frequency 2 impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)

  1. 2h m
  2. 2 h m
  3. h (2m)
  4. h m
NEET 2013
9

A source of light is placed at a distance of 50 cm from a photo cell and the stopping potential is found to be V0. If the distance between the light source and photo cell is made 25 cm, the new stopping potential will be :

  1. V0/2
  2. V0
  3. 4V0
  4. 2V0
NEET 2013 (Karnataka)
10

The de-broglie wavelength of neutrons in thermal equilibrium at temperature T is

  1. 3.08 T A
  2. 0.308 T A
  3. 0.0308 T A
  4. 30.8 T A
NEET 2013 (Karnataka)
11

If the momentum of an electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5\%. The initial momentum of electron will be

  1. 200 P
  2. 400 P
  3. P200
  4. 100 P
AIPMT 2012 (Mains)

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