Stuck in someone else's frames? break free!
UMBRA AND PENUMBRA
narrow end of a key between two stacks of books.
Now make the light source smaller by moving the light further away or by covering the shade of the lamp with a heavy piece of cardboard that has a small hole punched in the center. Shine the light on the key again. You will discover that when the light source is larger than the object upon which it shines, the shadow cast has two parts. The dark, inner part is called the umbra and the lighter, gray part is called the penumbra.
Use a diagram
to make an analogy to the earth (the key) and
shadows cast if the sun were smaller that the
umbrella is? It is the diminutive of the Latin
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