Question

Write the definition of umbra and penumbra

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

Penumbra:the partially shaded outer region of the shadow cast by an opaque object.

umbra:the fully shaded inner region of a shadow cast by an opaque object, especially the area on the earth or moon experiencing the total phase of an eclipse.

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