Aim: To find the average size of microbes in a water sample using laser microscope.
Apparatus: Water sample with microbe culture, syringe, laser source (wavelength = 635 nm), scale, retort stand, screen
A plastic syringe contains water sample with microbe culture. A water droplet is formed at the open end of the syringe when the piston of the syringe is gently pressed. A Laser beam is focused on the droplet. On the screen, we see a magnified image of the microbes present in the water droplet. Around the magnified image of the microbes, we observe a diffraction pattern. By studying this diffraction pattern, we will find their average size.
Schematic representation of the set-up
Fig.1 The photograph of the pattern obtained on the screen
The average size of microbes present in the given water sample is _______________