How Does a Shadow Know Where the Light Is?

Shadows follow the light because they can’t see it, but they know where it is. When a light moves, like the sun or a lamp, the shadow knows to move too! Imagine you're blocking sunlight with your hand, your shadow appears on the ground. If you walk toward the sun, your shadow gets shorter and follows you like a little friend. Shadows can’t see the light, but they react to it, just like how your shadow moves when you move.

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Examples

  1. Your shadow grows longer in the evening as the sun moves behind you.
  2. A tree casts a long shadow on the ground when it's early morning.
  3. When your friend walks away from the lamp, their shadow gets bigger.

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Categories: Physics · Light· Shadow· Optics · Text is available under the Creative Commons Attribution-ShareAlike License.