The Open Door Web Site : IB Physics : Practical Work : Observing Diffraction of Light using a Low Power Laser

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Waves and Optics

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Observing Diffraction of Light using a Low Power Laser

Never look directly at a laser light source.

1. Observe and draw the diffraction patterns produced by
	a)	single slits of different widths (note the width of the slit)
	b)	double slits of different slit separation (note the slit widths and separations)
	c)	multiple slits (note the number of slits per mm)

2. Use a diffraction grating to measure the wavelength,

, of the laser light.

For constructive interference

n = dsin

where	n = the order of the image (0, 1, 2…)
	d = the distance between two lines of the grating
	= the angular position of the image (measured from the normal to the grating)

By measuring D and y, can be found.
We can then calculate the wavelength, .