Interference and Diffraction Multiple Choice Questions and Answers

21. Diffraction is special type of

1. Reflection
2. Refraction
3. Interference
4. Polarization

22. Extended source is needed in

1. Youngs double slit experiment
2. Bi prism Experiment
3. Newtons Ring Experiment
4. None of them

23. Find the maximum value of resolving power of a grating 3 cm wide having 5000 lines per cm, if the wavelength of light used is 5890 A^o.

1. 40000
2. 45000
3. 4500
4. 5000

24. For all transparent material substances, the index of refraction

1. is less than 1
2. is greater than 1
3. is equal to 1
4. Could be any of the given answers; it all depends on optical density

25. Fraunhofer diffraction at a Plane Grating. What is the meaning of grating element for a diffraction grating?A It is the width of a single slit

1. It is the width of the opaque space
2. It is the distance between two slits
3. It is the width of diffraction grating

26. Fraunhofer diffraction is observed when

1. Only screen is placed at finite distance
2. source is placed at finite distance
3. neither source nor screen is at finite distance
4. None of these

27. Fresnels type diffraction is observed when

1. Only screen is placed at finite distance
2. Only source is placed at finite distance
3. Both source and screen are at finite distance
4. Neither source nor screen is at finite distance

28. Fringe spacing is defined as the distance between two Consecutive

1. Crests
2. Bright fringes only
3. Dark fringes only
4. Bright or dark fringes

29. 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

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

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