Question 9.1. In a young 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 bright band and the fifth bright fringe on the screen which is 3m away from the slit.

Question 9.2. Monochromatic light of wavelength 589.2 nm is used to illuminate the narrow slits 1mm apart. Find the positions of the first dark and the first bright fringes on the screen 100 cm away.

Question 9.3. Two parallel slits are illuminated by light of two wavelengths, one of the which is 5.8 x 10^-7 m. On the screen the fourth dark line of the known wavelength coincides with the fifth bright line of the light of unknown wavelength. Find the unknown wavelength.

Question 9.4. When the movable mirror of a Michelson Interferometer is moved 0.1 mm. How many dark fringes pass through the reference point, if light of wavelength 580 nm is used?

Question 9.5. When the movable mirror on 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.

Question 9.6. 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 mm falls on it normally?

Question 9.7. Find the polarizing angle for a glass of refractive index of 1.55.

Question 9.8. 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?

Question 9.9. Light is incident normally on a grating which has 250 lines/ mm. Find the wavelength of spectral line for which the deviation in second order is 12°.

Question 9.10. In a certain X-rays diffraction experiment the first order image is observed at an angle of 5° for a crystal plane spacing of 2.8 x10^-10 m. What is the wavelength of X-rays used?