F.5 Phy Light waves20marks

chi ming

2011-02-26 7:57 am

1. I n a double-site experiment using red light, how would the fringe pattern projected on a screen be affected if
a) the separation of the slits is increased;
b) the screen is moved further away;
c) blue light,which is of shorter wavelength,is used instead;
d) the whole set-up is put in oil?

2. In young's double-site experiment, can we replace the double-slit with two lamps?Explain briefly.

3. Explain briefly why monochromatic light is preferred in studying the interference of light using a double-slit.

回答 (1)

天同

2011-02-26 8:51 am

✔ 最佳答案

1. (a) The fringe separation decreases.
(b) The fringe separation increases.
(c) The fringe separation decreases.
(d) The fringe separation decreases.

The following web-page gives a good animation of the double slit interference pattern. You could play with it by varying the slit separation, wavelength etc and observe how the fringe separation changes

http://www.walter-fendt.de/ph14e/interference.htm

2. No. Light from the lamps are incoherent waves. This would not produce an interference pattern.

3. If light composes of different wavelengths is used, the interference pattern of different colours would overlap each other. This makes observation of the fringe pattern difficult.

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