Light & Sound

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Lesson 1

Light travels from a luminous source in straight lines. Unlike most waves, light can travel to a vacuum, a space with no matter in it.

When light hits an object, it can either be absorbed, reflected, or transmitted. Objects that do not let light transmit through them are called opaque objects. Ones that let some light transmit through them are called translucent objects, and ones that do not let light transmit through them are opaque. When light hits an opaque object, it stops the light from passing through as it reflects and/or absorbs everything- therefore, an area where light does not hit is created; a shadow.

Nothing can travel faster than light (at least not any that we are currently aware of). Light, at 300,000 km/s, clearly beats sound which travels at about 340 m/s which explains why we often see lighting flashes a few moments before we hear thunder.

Lesson 2

An object that produces light is called a luminous object. Some examples of luminous objects include