Brownian motion

Brownian motion describes the random movement of particles suspended in a liquid or gas, originally discovered by Robert Brown in 1827, looking at pollen grains in water.

EQUIPMENT:

√ Light microscope with 40x objective (10x eyepiece) lenses

√ Solution of milk and water, whole or semi-skimmed milk works well (approx. 10 cm3 water with 2 - 3 drops of milk)

√ Microscope slide/microscope cavity slide and cover slip

METHOD:

1. Place 1 - 2 drops of water/milk solution onto a slide or cavity slide if available.

2. Add a coverslip – try to avoid air bubbles.

3. Place the slide under the microscope and turn the condenser so that there is minimal light coming onto the image.

4. Focus the image (remember you are looking for milk and water particles – not an easy combination to see), try focussing on a prepared slide first and then swap it out for your Brownian motion slide.

It is the use of contrast and focus that allows a good view of the fat particles of the milk moving in this demonstration and it can be tricky to get right. You may have to play with the light levels on the stage (condenser) as well as the focussing. The key is patience and calmness.

Milk fat particles

Our product specialists are happy to demonstrate our range of microscopes.

Products:

The Motic SFC-100FLED is a robust microscope with high-quality optics and LED illumination, it runs cool and has built-in rechargeable batteries.

The Motic F-1115 LED is simple to handle with magnification up to x100 and a built-in Abbe condenser.

The Motic B1-220E-SP binocular microscope features semi-plan objectives, magnification up to x400 and a built-in mechanical stage.

Looking for high-quality physics equipment? Try the Frederiksen range.

Not everybody is meant to be a scientist. However, Frederiksen believe that everybody has the right to learn. They provide science equipment that is well-designed, simple to use and tailored for teaching. Their aim is to engage students to learn and teachers to teach!