Question

________________ is a completely dark portion of a shadow.

Answer 1

1. The central and darkest part of a shadow is called an umbra.
2. If you aim a light source directly at an object, the blackest portion of the shadow directly behind the object is the umbra of the shadow.
3. The darker part of the shadow is called the umbra, where the light source is completely blocked by the occluding body.
4. The region surrounding the umbra is called the penumbra.
   Umbra. is a completely dark portion of a shadow.