Physical Optics MCQs for MDCAT Practice

Physics section, Physical Optics chapter. Sample questions from past PMC papers.

1. Question 1
   The phenomenon of polarization of light reveals that light wave
   • A.Are longitudinal.
   • B.Are extremely short.
   • C.Have a long wavelength.
   • D.Are transverse electromagnetic.
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2. Question 2
   The narrow slits of a diffraction grating are 5 × 10-4m apart. If a light ray of 5 × 10-7 m wavelength passes through the narrow slits, then the value of angle observed at the third-order bright spot is
   • A.0.057°
   • B.0.028°
   • C.0.017°
   • D.0.085°
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3. Question 3
   All of the following are the conditions necessary for the interference of light EXCEPT
   • A.Light waves should be monochromatic.
   • B.Sources of the light waves must be coherent
   • C.Identical light waves should have constant phase difference.
   • D.Size of the obstacle must be similar to the wavelength of light waves.
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4. Question 4
   In Young’s double slit experiment the separation d between the slits is 2mm, the wavelength of the light used is 5896 A and the distance D between the screen and slits is 100cm. It is found that the angular width of the fringes is 0.20. To increase the fringe angular width to 0.21 with the same wavelength and D, the separation between the slits needs to be changed to
   • A.1.8 mm
   • B.2.1 mm
   • C.1.7 mm
   • D.1.9 mm
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5. Question 5
   Which of the following phenomena reveals that light waves are transverse waves? I. Diffraction П. Polarization III. Interference
   • A.I only
   • B.I and III
   • C.II and III
   • D.II only
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6. Question 6
   If a man moves, with a speed equal to 0.5 that of sound, away from a stationary source generating sound of frequency of 1000Hz, he would probably hear sound of frequency:
   • A.1000 Hz
   • B.750 Hz
   • C.667 Hz
   • D.500 Hz
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7. Question 7
   In Young`s double slit experiment, if d is separation between two slits, is wavelength of light and is angle of line from center of slits to the point of observation on the screen; then for maxima (bright fringe); the formula is _______
   • A.2dsin = m; m = 0, 1, 2, ...
   • B.dsin = (m+1/2); m = 0, 1, 2, ...
   • C.2msin = d; m = 0, 1, 2, ...
   • D.dsin = m; m= 0, 1, 2, ...
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8. Question 8
   In diffraction of light around an obstacle, the angle of diffraction is increased then:
   • A.The wavelength of incident light wave is decreased
   • B.The amplitude of the incident light wave is increased
   • C.The amplitude of the incident light wave is decreased
   • D.The wavelength of incident light wave is increased
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