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1. AcTIVITY 6
AIM
To observe diffraction of light due to a thin slit between sharp edges of razor blades.
APPARATUS REQUIRED
Two microslides, two razor
blades, adhesive tapes, a screen and laser pencil, black paper.
PRINCIPLE
The bending of light around sharp obstacles, apertures or corners is called diffraction. For the occurrence of this
phenomenon the siZe of obstacle etc. should be comparable to the wavelength of incoming light. The angle of diffraction
for different orders (n) of diffraction is given as:
d sin 0 = na
Pattern on screenn
(Fig. 1. Diffraction of light)
PROCEDURE
1. Paste black paper on a glass plate. Keep razor blades on top of it so that there is very minute gap between their
edges. Make a slit in black paper in the gap between two edges of the blades.
2. Place this system in front of light source and observe the pattern of light falling on the wall.
3. It will be observed that instead of a single band corresponding to the slit there are bands on either side of the
slit with decreasing intensity.
4 This shows how diffraction happens when light passes through a slit.