Schematic illustration of a magnifying lens.

Shadow Look

How Does a Magnifying Lens Affect Shadows?

 

Materials

  • piece of white cardboard
  • plastic cup
  • ruler
  • flashlight
  • magnifying lens

Try This

  1. Place the piece of cardboard on the floor so it is leaning against a wall.
  2. Place the plastic cup on the floor about 8 in. (20 cm) in front of the cardboard.
  3. Direct the flashlight beam on the cup and look at the shadow cast on the cardboard.
  4. Place the magnifying lens between the cup and the cardboard.
  5. Again, direct the flashlight beam on the cup.
  6. Move the flashlight back and forth to get a clear shadow. Is the shadow larger or smaller than the shadow that was cast without the magnifying lens?

What's Going On?

The shadow cast by the cup was smaller when the magnifying lens was placed between the cup and the cardboard. A shadow is the absence of direct light rays. When you placed the magnifying lens in front of the cup, it picked up the rays coming around the outside of the cup and bent them inward. Because the magnifier channeled this light to the cardboard, the cup's shadow was smaller.

Schematic illustration of a piece of white cardboard, a plastic cup, a ruler, a flashlight, and a magnifying lens.