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Engineering Physics Practice Test: Diffraction
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Diffraction topics include: Light diffraction, plane diffraction grating, prism and grating spectra difference, grating resolving power, fresnel and fraunhofer diffraction. Diffraction is the bending or spreading out of waves as they pass through an obstacle or aperture. It can occur with sound, electromagnetic radiation, and very small moving particles.  Diffraction occurs when the size of the obstacle or aperture is similar to the wavelength of the incident wave. For example, when light waves pass near a barrier, they bend around the barrier and spread out.  Diffraction can also occur... Show more
Engineering Physics Practice Test: Diffraction
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25 Questions

1. Our eyes see two objects as separate, only if the angle subtended by them at the eye is greater than _________
2. If the Fresnel’s distance is a, then what should be the distance of the screen from the slit, d, such that ray optics is no longer valid?
3. Light is incident normally on a grating of width 5 X 10-3 m with 2500 lines. What is the resolving power of the grating in the second order spectrum?
4. How many lenses are used in Fraunhofer Diffraction?
5. What is the highest order spectrum which may be seen with a monochromatic light of wavelength 5000 Å by means of a diffraction grating with 5000 lines/cm?
6. Which graph is shown in the figure?
The figure shows the variation of intensity with the number of exposed zones
7. A diffraction pattern is obtained with a straight edge using light of wavelength 5500 Å. The separation between the edge and the source is 15 cm while that between the edge and the eyepiece is 3 m. What is the position of the first maximum?
8. What is the minimum number of lines per cm in a 2.5 cm wide grating spectrum which will just resolve two sodium lines (5890 Å and 5896 Å) in the first order spectrum?
9. Which of the following lines represent the resolution of a prism?
X is resolution of prism, Y is resolution of diffraction grating & Z is QE of camera
10. A screen is placed 2m away from the lens to obtain the diffraction pattern in the focal plane of the lens in a single slit diffraction experiment. What will be the slit width if the first minimum lies 5 mm on either side of the central maximum when plane light waves of wavelength 4000 Å are incident on the slit?
11. Which of the following is the correct expression for the resolving power of a grating?
12. Find the missing order for a double-slit Fraunhofer Diffraction pattern if the slit widths are 0.2 mm separated by 0.6 mm.
13. In Double Slit Fraunhofer Diffraction, some orders of interference pattern are missing. It is called ____________
14. The surface of calculation for Fraunhofer and Fresnel diffraction patterns are respectively __________
15. A grating has 16000 per inch over a length of 5 inches. What will be the smallest wavelength difference for a light of wavelength 6000 Å?
16. If there are N number of slits in a grating spectra, then there will be how many secondary maximas?
17. If the separation between the two slits in Double Slit Fraunhofer Diffraction is changed, what change will be observed in the diffraction pattern?
18. A screen is placed 2m away from the lens to obtain the diffraction pattern in the focal plane of the lens in a single slit diffraction experiment. What will be the slit width if the first minimum lies 5 mm on either side of the central maximum when plane light waves of wavelength 4000 Å are incident on the slit?
19. The resolving power of a grating is directly proportional to grating constant.
20. Light of 4000 Å is incident on a circular hole of radius 3 cm. How many half-period zones are contained in the circle if the screen is placed at a distance of 0.5 m?
21. What is the relation between the dispersive power, D, of a grating and the order, n, of a spectrum?
22. Which of the following is the correct expression for the ratio of the intensity of principal maxima to the intensity of secondary maxima?
23. If a light is incident on a grating with 5000 lines/cm, then the angular separation of the two lines (5000 Å and 5006 Å) in first order spectrum is ______
24. The spectrum observed for a grating is much purer than a prism.
25. X-ray crystallography uses which characteristic of light?