Name: Umbra and Penumbra
Uploaded: 2019-07-19
Duration: 2 min 12 s
Description: Penumbra and umbra are terms for the parts of shadows; basically, the umbra is the darkest area, and the penumbra is the lighter region. Let's watch the video.

Question

Complete the crossword puzzle using the hints given below.

Across
1. Wooden board is an example of this type of material.
5. A pinhole camera works on the principle of such propagation of light.

Down
2. The region of complete darkness in a shadow.
3. Butter paper is an example of this type of material.
4. They are formed when light is obstructed by an opaque object.
6. An important characteristic of glass.
7. It creates a sense of vision in us.

Accepted Answer

Across

1. A wooden board is an example of opaque material as it blocks the path of light.
5. A pinhole camera works on the principle of rectilinear propagation of light which means light rays always travel in a straight path.

Down

2. The region of complete darkness in a shadow is called Umbra.
3. Butter paper is an example of a translucent material as it allows some part of the light to pass through it and blocks the rest.
4. Shadows are formed when light is obstructed by an opaque object.
6. Glass is a transparent material light can easily pass through it. It does not cast a shadow.
7. Light is a form of energy that gives us a sense of vision. For example, Light from a Sun, falls on the object it reflects light in all possible directions. The reflected light from the object reaches our eyes and our brain receives the information from the eyes making us see the object.

Hence,

Important Questions on Light

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