Name: Solar and Lunar Eclipses
Uploaded: 2019-07-19
Duration: 7 min 27 s
Description: Solar and lunar eclipses are celestial phenomena that occur when the Sun, Moon and Earth align in a way. Watch this video to understand the phenomenon.

Question

Explain the umbra and penumbra regions of a shadow.

Accepted Answer

Sometimes the centre of the shadow is darker than its surroundings, which is lighter. So, a shadow can have two regions. They are called as umbra region and penumbra region. Umbra is the darkest and innermost part of a shadow. Umbra is formed when the object completely blocks the light source. When we have a point source of light, only umbra is formed on the screen. This is because the object blocks the light completely and a sharp and dark shadow is formed on the screen.

The region from where the observer experiences partial darkness of the shadow is called the penumbra. Some light falls in the penumbra region when the object is not able to block the source of light completely. Hence, this region is partially dark. When we have a broad source of light, both umbra and penumbra are formed on the screen.

Explain the umbra and penumbra regions of a shadow.

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