Important Questions of Dual Nature of Radiation and Matter Physics | Zigya

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171.

The speed of an electron having a wavelength of 10-10 m is

  • 7.25 × 106 m/s

  • 5.25 × 106 m/s

  • 6.26 × 106 m/s

  • 4.24 × 106 m/s


172.

Colour of star depends upon

  • luminosity

  • temperature

  • brightness

  • all of these


173.

The work function of a metal is 3.4 eV. If the frequency of incident radiation is increased to twice, then the work function of the metal becomes

  • 3.4 eV

  • 7.2 eV

  • 6.8 eV

  • 1.7 eV


174.

If red light is replaced by white light then width of diffraction pattern will

  • increases

  • decreases

  • a central white band is obtained

  • no effect


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175.

In Planck's oscillator energy is given as

     E = exp Kt - 1   If K = 0, then energy would be

  • 0

  • Kt


176.

Assertion: On increasing the frequency of light larger number of photoelectrons are emitted. 

Reason:  The number of electrons emitted depends on the intensity of incident light.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reasonn are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If assertion is false but reason is true.


177.

Maximum velocity of photoelectron emitted is 4.8m/s. If e/m ratio of the electron is 1.76 × 1011 CKg-1 then stopping potential is given by

  • × 10-10 J/C

  • × 10-7 J/C

  • × 10-11 J/C

  • 2.5 × 10-2 J/C


178.

The de-Broglie wavelength of an electron having 80 eV of energy is nearly (1 eV = 1.6 × 10-19J, mass of electron = 9.1 × 10-31 kg, Planck's constant = 6.6 × 10-34 J-s)

  • 140 Å

  • 0.14 Å

  • 14 Å

  • 1.4 Å


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179.

When light of wavelength 300 nm falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, light of wavelength 600 nm is sufficient for liberating photoelectrons. The ratio of the work function of the two emitters is

  • 1 : 2

  • 2 : 1

  • 4: 1

  • 1: 4


180.

Maximum velocity of the photoelectrons emitted by a metal surface is 1.2x106 ms-1. Assuming the specific charge of the electron to be 1.8 x1011 C kg-1, the value of the stopping potential in volt will be

  • 2

  • 3

  • 4

  • 6


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