Observing Brownian Motion

Brownian motion is the random movement of particles. It is possible to observe this movement under the microscope.

Materials: milk, water, slide, cover slip


  1. Dilute one drop of milk in about 5ml of water.
  2. Place one drop of the dilute milk on the microscope slide and place a cover slip on top of it.
  3. Observe under the microscope in bright field and in dark field. The microscopic fat droplets of the milk can be seen moving randomly. This is Brownian motion.
  4. Change the temperature by placing the slide into the refrigerator or by warming it up. Observe again. The Brownian motion is temperature dependent.

2 thoughts on “Observing Brownian Motion”

  1. Cool. But I found better results (in terms of globule concentration) by mixing 4 drops of pasteurized milk with 5ml of distilled water.

Comments are closed.