The speed of electromagnetic waves in vaccum is from Physics Ele

Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsMultiple Choice Questions

81.

If vg, vx and vm are the speeds of gamma rays, X rays and microwaves respectively in vacuum then :

  • vg > vm > vx

  • vg > vx > vm

  • vg = vm = vx

  • none of these


82.

The minimum wavelength of X-rays emitted by X-ray tube is 0.4125 Å. The accelerating voltage is :

  • 30 kV

  • 50 kV

  • 80 kV

  • 60 kV


83.

An electron beam is accelerated through a potential difference of V volt. The minimum wavelength of X-rays produced is :

  • hecV

  • cVhe

  • eVhc

  • hceV


84.

Light waves of wavelength λ is incident on a metal of work function φ . Maximum velocity of the electron is :

  • 2(-φ)m1/2

  • 2(hc-λφ)1/2

  • 2(hc-λφ)m

  • hc+λφ1/2


Advertisement
85.

Spectrum of a star is shifting towards voilet colour, then the star

  • is going away from earth

  • is coming towards earth

  • intensity of light of star is increasing

  • intensity of light of star is decreasing


86.

X-rays are not used for radar purposes because they are not

  • reflected by target

  • partly absorbed by target

  • electromagnetic waves

  • completely absorbed by target


87.

The minimum wavelength of X-ray emitted by X-ray tube is 0.4125 A. The accelerating voltage is

  • 30 kV

  • 50 kV

  • 80 kV

  • 60 kV


88.

The nature of light waves is similar to

  • cosmic rays

  • cathode rays

  • gamma rays

  • alpha rays


Advertisement
89.

The energy of an X-ray photon is 2 keV, then its frequency will be

  • 3.2 x 10-6 per second

  • 5 x 1017 per second

  • 2 x 1017 per second

  • 2 × 1018 per second


Advertisement

90.

The speed of electromagnetic waves in vaccum is

  • µ0ε0

  • 1μ0ε0

  • μ0ε0

  • 1μ0ε0


B.

1μ0ε0

The electromagnetic waves travel with the speed of light in vacuum and it is given as

         c = 1μ0ε0


Advertisement
Advertisement