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Q: The region where all of the light from the source is blocked is called:
  • A. Penumbra
  • B. Umbra
  • C. Antumbra
  • D. Shadow
Correct Answer: Option B - The umbra, penumbra and antumbra are three distincts, parts of a shadaw, created by any light source after impinging on an opaque object. When an opaque object is placed between an extended source of light and a screen, we obtain, on the screen, a shadow consisting of two parts, an inner part which is perfectly dark and called umbra and an outer part called penumbra which is partialy illuminated. The antumbra is the region from which the occluding body appears entirely within the disc of the light source.
B. The umbra, penumbra and antumbra are three distincts, parts of a shadaw, created by any light source after impinging on an opaque object. When an opaque object is placed between an extended source of light and a screen, we obtain, on the screen, a shadow consisting of two parts, an inner part which is perfectly dark and called umbra and an outer part called penumbra which is partialy illuminated. The antumbra is the region from which the occluding body appears entirely within the disc of the light source.

Explanations:

The umbra, penumbra and antumbra are three distincts, parts of a shadaw, created by any light source after impinging on an opaque object. When an opaque object is placed between an extended source of light and a screen, we obtain, on the screen, a shadow consisting of two parts, an inner part which is perfectly dark and called umbra and an outer part called penumbra which is partialy illuminated. The antumbra is the region from which the occluding body appears entirely within the disc of the light source.