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?
 
  • The angular width of the central maximum of the diffraction pattern will increase.
  • The angular width of the central maximum will decrease.
  • The angular width of the central maximum will be unaffected.
  • A diffraction pattern is not observed on the screen in the case of electrons.

Two periodic waves of intensities I1 and I2 pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is

  •   2l1+l2

  •   I1+l22

  •   I1-l22

  •   2I1-l2

A major breakthrough in the studies of cells came with the development of an electron microscope. This is because:

  • the resolution power of the electron microscope is much higher than that of the light microscope.

  • the resolving power of the electron microscope is 200-350 nm compared to 0.1-0.2 nm for the light microscope.

  • electron beam can pass through thick materials, whereas light microscopy requires thin sections.

  • the electron microscope is more powerful than the light microscope as it uses a beam of electrons that has a wavelength much longer than that of photons.

In a double-slit experiment, when the light of wavelength 400 nm was used, the angular width of the first minima formed on a screen placed 1 m away, was found to be 0.2°. What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water? μwater=4/3

  • 0.1°

  • 0.266°

  • 0.15°

  • 0.05°

In Young's double-slit experiment, if there is no initial phase difference between the light from the two slits, a point on the screen corresponding to the fifth minimum has path difference :

  •  5λ2

  •  10λ2

  •  9λ2

  •  11λ2

The angular width of the central maximum in the Fraunhofer diffraction for λ=6000 Ao is θ0. When the same slit is illuminated by another monochromatic light, the angular width decreases by 30%. The wavelength of this light is:

  •  1800 Ao

  •  4200 Ao

  •  420 Ao

  •  6000 Ao

The number of fringes in the field of view of YDSE is 30 in air. If the experiment is performed in water μ=43, then the number of fringes in the field of view will be 

  • 30

  • 50

  • 40

  • 60 

Which of the following property of light is a sure proof of wave nature of light?

  •   Interference 

  •   Diffraction

  •   Photoelectric Effect

  •   Both (1) & (2)

In Young's double slit experiment, a slit is covered with a thin film so that the optical path difference introduced between coherent waves is 5λ. Then the new position of central maxima will be at

 

  •   The initial position of 5th maxima

  •   The initial position of 3rd minima

  •   The initial position of 2nd minima

  •   The initial position of 3rd maxima

In Young's double-slit experiment using the light of wavelength 'λ', 60 fringes are seen on a screen. If the wavelength of light is decreased by 50%, then the number of fringes on the same screen will be:

  •   30

  •   60

  •   120

  •   90

The polarising angle for the material is 60°, then the refractive index of a material is:

  •   13

  •   32

  •   3

  •   32

The geometrical path of a ray of light in a medium of refractive index 2 is 8 m. The optical  path is

  •   16 m

  •   4 m

  •   2 m

  •   1 m

In Young's double-slit experiment if the separation of the screen is increases from slits, the fringe width will 

  •   Decrease

  •   Increase

  •   Remain the same

  •   Any of the above depending on the wavelength of the light used

Five identical polaroids are placed coaxially with 45° angular separation between pass axes of adjacent polaroids as shown in the figure. ( Io: Intensity of unpolarized light)
          
The intensity of light, I, emerging out of 5th polaroid is

  •   I04

  •   l08

  •   l016

  •   l032

In Young's double-slit experiment, how many minimas can be obtained on a screen, if the wavelength of light used is 2000 Ao and slit width is 0.0008 mm?

  •   6

  •   7

  •   8

  •   9

When YDSE is carrying out in liquid, 5th bright fringe lies at a point on the screen where 3rd dark fringe was lying in the air. The refractive index of the medium is

  •   1.5

  •   3

  •   2

  •   1.2

In Y.D.S.E., the ratio of maximum intensity at a point to the intensity at the same point when one slit is closed, is:

  •   2

  •   3

  •   4

  •   1

Two light waves given below superimpose at a point.

y1=asin2πty2=2asin2πt+π3.

The resultant amplitude of the waves is

  •   a6

  •   a5

  •   a3

  •   a7

When a transparent sheet of thickness t and refractive index μ is introduced in one of the paths in YDSE having slit width d and distance between slits and screen is D, then the fringe pattern shifts by

  •   dDμ-1t

  •   dDμ-1t

  •   Ddμ-1t

  •   dtμ-1D

Which statement is not true for the polarization of light?

 

  •   Light vibrations are restrained only in one plane.

  •   Establishes the longitudinal nature of light.

  •   The intensity of light decreases.

  •   Both (2) & (3)

The intensity of the polarized light becomes 1a times its initial intensity. The angle between the axis of analyzer and polarizer is

  •   θ = tan-1a-1

  •   θ = tan-11a

  •   θ = sin-1a-1

  •   θ = sin-11a

Which statement is true for interference?

  •   Two independent sources of light can produce interference pattern.

  •   There is no violation of conservation of energy.

  •   White light cannot produce interference.

  •   The interference pattern can be obtained even if coherent sources are widely apart.

In Y.D.S.E., if the intensity ratio of bright and dark fringes is 81: 25. The ratio intensity of two waves is

  •   1: 49

  •   49: 4

  •   1: 4

  •   4: 40

Two monochromatic waves each of amplitude A have a phase difference π2 between them. When they superimpose, the amplitude of the resultant wave is

  •   2A

  •   Zero

  •   4A

  •   A2

A screen is placed 100 cm from a single slit which is illuminated with 5000 Ao light. If the distance between the first and third minima in the diffraction pattern is 5 mm. The width of the slit is

  •   2 mm

  •   0.2 μm

  •   2 ×10-4 m

  •   4 ×10-5 m

When the light of a certain wavelength is incident on a plane surface of a material of a glancing angle 30°, the reflected light is polarised. The angle of refraction is

  •   60°

  •   30°

  •   45°

  •   40°

In a double-slit experiment, the distance between the slit is d. The screen is at a distance D from the slits and λ is the wavelength of light used. If a dark fringe is formed opposite to a slit on the screen, the order of fringe is

  •   d2+λD2λD

  •   -D+d2λ

  •   Dλ+d2D

  •   D2+dλ2λ

In Y.D.S.E., if a liquid is filled between the space of the screen and slit, then

  •   Central bright fringe will shift upward.

  •   Central bright fringe will not shift.

  •   Central bright fringe will shift downward.

  •   Central fringe may shift downward or upward.

In Y.D.S.E. if the width of the slits is gradually decreased, then

  •   Bright fringe will become brighter and dark fringe becomes darker.

  •   Bright fringe becomes less bright and dark fringe becomes less dark.

  •   Bright fringe becomes brighter and dark fringe becomes lighter.

  •   Bright fringe becomes less bright and dark fringe becomes darker.

Light waves of intensities l and 9l interfere to produce a fringe pattern on a screen. The phase difference between the waves at a point P is 3π2 and 2π at other point Q. Then the ratio of intensities at P and Q is:

 

  •   8: 5

  •   5: 8

  •   1: 4

  •   9: 1

0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Physics Quiz Questions and Answers