Subject

Physics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

61.

The intensity of gamma radiation from a given source is I. On passing through 36 mm of lead, it is reduced to l/8. The thickness of lead which will reduce the intensity to l/2 will be

  • 6 mm

  • 9 mm

  • 18 mm

  • 18 mm

625 Views

62.

The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480 nm is incident on it. The band gap in (eV) for the semiconductor is

  • 1.1 eV

  • 2.5 eV

  • 0.5 eV

  • 0.5 eV

284 Views

63.

A photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed 1 /2 m away, the number of electrons emitted by photocathode would

  • decrease by a factor of 4

  • increase by a factor of 4

  • decrease by a factor of 2

  • decrease by a factor of 2

225 Views

64.

Starting with a sample of pure 66Cu, 7/8 of it decays into Zn in 15 minutes. The corresponding half-life is

  • 10 minutes

  • 15 minutes

  • 5 minutes

  • 5 minutes

452 Views

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65.

If radius of  nucleus is estimated to be 3.6 Fermi then the radius nucleus

  • 6 fermi

  • 8 fermi

  • 4 fermi

  • 4 fermi


A.

6 fermi

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66.

A Young’s double slit experiment uses a monochromatic source. The shape of the interference fringes formed on a screen is

  • hyperbola

  • circle

  • straight line

  • straight line

390 Views

67.

A fish looking up through the water sees the outside world contained in a circular horizon. If the refractive index of water is 4/3 and the fish is 12 cm below the surface, the radius of this circle in cm is

  • 36 square root of 7
  • 36 divided by square root of 7
  • 36 square root of 5
  • 36 square root of 5
287 Views

68.

Two point white dots are 1 mm apart on a black paper. They are viewed by eye of pupil diameter 3 mm. Approximately, what is the maximum distance at which these dots can be resolved by the eye? [ Take wavelength of light = 500 nm ]

  • 5 m

  • 1 m

  • 6 m

  • 6 m

275 Views

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69.

A thin glass (refractive index 1.5) lens has an optical power of – 5D in air. Its optical power in a liquid medium with refractive index 1.6 will be

  • 1 D

  • 5/8 D

  • -1 D

  • -1 D

165 Views

70.

The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy?

  • lll

  • IV

  • I

  • I

270 Views

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