Question

What is umbra and preumbra?

Answer 1

The umbra, penumbra and antumbra are three distinct parts of a shadow, created by any light source after impinging on an opaque object. Assuming no diffraction, for a point source only the umbra is cast.

Answer 2

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The umbra is the dark center portion of a shadow. The Moon's umbra causes total solar eclipses, and the Earth's umbra is involved in total and partial lunar eclipses. ... Each shadow has 3 different areas: the umbra, the penumbra, and the antumbra.

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