# Which property of light makes a pencil cast a shadow when it is held in front of a light source?

Light travels in a straight line, this is the property of light that makes a pencil cast a shadow when it is held in front of a light source.

Explanation

General characteristic of light are as follow:

1. Light is a form of energy produced by luminous objects.

2. Light travels in a straight line.

3. Light can travel through a vacuum.

4. Light can be reflected.

5. Light can be bent/refracted.

6.  Light travels with a speed of 3.0 $\times$ 108 m/s in a vacuum.

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