## Numerical Problems, Physical Optics

This page consists of solved numerical problems of Physical Optics included in the First Year Physics course.

S No Problem
Problem 1 In a Young’s double slit experiment, the separation of the slits is 1 mm and red light of wavelength 620 nm is falling on it. Determine the distance between the central bight band and the fifth bright fringe on the screen which is 3 m away from the slit.
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Problem 2 Monochromatic light of wavelength 589.2 nm is used to illuminate the narrow slits 1 mm apart. Find the position of the first dark and first bright fringes on a screen 100 cm away.
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Problem 3 Two parallel slits are illuminated by two wavelengths one of which is 5.8 × 10-7 m. On the screen the fourth dark line of the known wavelength coincides with the fifth bright line of the light of the unknown wavelength. Find the unknown wavelength.
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Problem 4 When the movable mirror of the Michelson interferometer is moved 0.1 mm. How many dark fringes pass the reference point if light of wavelength 580 nm is used?
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Problem 5 When the movable mirror of a Michelson interferometer is moved in one direction, 400 fringes appear to pass through the field of view when light of wavelength of 500 nm is used. What is the distance through which the mirror has been moved?
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Problem 6 A soap film has a refractive index of 1.40. How thick must the film be, if it appears black when mercury light of wavelength 546.1 nm falls on it normally?
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Problem 7 Find the polarizing angle for a glass of refractive index 1.55?
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Problem 8 A diffraction grating has 5000 lines per centimeter. At what angle does the second order spectrum of the sodium yellow light of wavelength 589 nm occur?
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Problem 9 Light is incident normally on a grating which has 250 lines/mm. Find the wavelength of the spectral line for which the deviation in second order is 12o.
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Problem 10 In a certain X-rays diffraction experiment, the first order fringe is observed at an angle of 5o for a crystal plane spacing of 2.8 × 10-10 m. What is the wavelength of X ray used?
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Problem 11 An X-ray beam of wavelength 0.48 × 10-10 is used to get Brag reflection from a crystal at an angle of 20o for the first order maxima. What are the possible layer spacing which gives rise to this
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