Interference and Diffraction Multiple Choice Questions and Answers

11. How the intensity of secondary maxima varies in case of Fraunhofer diffraction pattern for single slit?

1. Intensity of secondary maxima decreases on either sides
2. Intensity of secondary maxima remains constant on either side
3. Intensity increases and decreases alternately
4. Intensity of secondary maxima increases on either sides

12. If we narrow the distance between two slits in Youngs experiment the fringes width

1. Increases
2. Decreases
3. Remains same
4. becomes zero

13. If you look perpendicular at thin film and move yourself away from the film (staying perpendicular to the film), you will notice

1. Reflected light becomes brighter and brighter
2. Reflected light becomes darker and darker
3. Reflected light alternates between darker and brighter
4. None of the Above

14. In a longitudinal wave

1. The particles move parallel to the direction of the wave motion.
2. The particles move perpendicular to the direction of the wave motion.
3. Energy causes the particles to move forward with the wave.
4. Energy is propagated by crests and troughs.

15. In a Youngs double-slit experiment the center of a bright fringe occurs wherever waves from the slits differ in the distance they travel by a multiple of

1. a fourth of a wavelength
2. a half a wavelength
3. a wavelength
4. three-fourths of a wavelength

16. In case of thin film of non-uniform thickness, when illuminated with white light, the film appears colored. This is due to change of what factor?

1. Conditions for path difference at different points of film
2. Change in optical path difference at different points of film
3. Thickness of film is different at different points of film
4. All of above

17. In diffraction Fraunhofer diffraction pattern due to single slit central maxima is formed at center because

1. Lens focuses all the diffracted rays at the centre of the slit
2. Slit focuses all the diffracted rays at the centre of the slit
3. Light rays focused at the centre of the screen undergo constructive interference
4. Slit and lens both combined focuses the rays at the centre of the slit

18. In diffraction pattern of monochromatic light the bright bands formed are

1. of uniform intensity
2. of non-uniform intensity
3. of uniform width
4. is of different colors

19. In Fraunhofer diffraction pattern for single slit, a central maximum is obtained when angle of diffraction q is equal to zero. What it actually indicates?

1. All the diffracted rays are parallel and focused by slit at a single point on screen
2. All the diffracted rays are perpendicular and focused by slit at a single point on screen
3. The rays are diffracted by the slit in all the directions
4. The rays are reflected by the slit

20. In Fraunhofer diffraction wave front used is

1. Spherical
2. Circular
3. Plane
4. Conical