Thin Films

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A thin film is a material which is a few nanometers to micrometers thick. The thickness is approximately equal to the wavelength of visible light. Thin films are synthesized using techniques like physical deposition, sputtering, and chemical deposition. Scientists exploit their thickness in applications like hard disks, solar cells, computer chips, mirrors, and LEDs.

In this activity, a user will use an ordinary black construction paper and clear nail polish to understand the formation and behavior of thin films in visible light. Parent supervision is advised.

What you need

  • A small sheet of black construction paper
  • Clear nail polish
  • A shallow pan or container
  • Water
  • Paper towels

What to do

  1. Fill the shallow pan or container container three quarters full with water.
  2. Slide the paper in the water, making sure it is completely submerged.
  3. Drop a couple of drops of the clear nail polish in the water.
  4. The nail polish should spread out in the form of a film in a minute
  5. Carefully slide the paper under the nail polish film and lift it out slowly.

What you’ll see

After you take the paper out you will see that the nail polish is not clear anymore and it sticks on to the paper

What’s going on?

The nail polish forms a thin film of few nanometers on the paper. The visible light interacts with the thin film and creates a rainbow-like pattern. Depending on the thickness, the patterns will look different.

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Thin films: