Light

What I should already know:

  • Light is reflected from surfaces.

  • The sun is the main source of light and can be very dangerous. There are ways we can protect our eyes.

  • Shadows are formed when the light from a light source is blocked by an opaque object.

  • The size of the shadow depends on the time of the day.


Key Vocabulary


Vocabulary Definition

Absorption

The process in which one thing absorbs something else.

Opaque

Doesn't let light through.

Reflected

Give something back without absorbing it.

Refraction

The change in direction of a wave passing from one medium to another or from a gradual change in the medium.

Shadows

A dark area or shape produced by a body coming between rays of light and a surface.

Translucent

Allowing light, but not detailed shapes, to pass through: semi-transparent.

Translucent

Allowing light, but not detailed shapes, to pass through: semi-transparent.

Transparent

Allowing light to pass through so that objects behind can be distinctly seen.

How light travels:

Watch the video below to discover how light travels:

  • Light travels in straight lines- this is why why shadows have the same shape as the objects that cast them.

  • We see things because light travels from light sources to our eyes or from light sources to objects and then to our eyes. See the diagram below:

  • When light passes through objects it slows down. Light also refracts when travelling through liquids such as water. This makes objects under a water surface appear closer than they really are.

  • When light enters, exits or changes the medium it travels in, at an angle, one side or the other of the wavefront is slowed before the other. This asymmetrical slowing of the light causes it to change the angle of its travel. Once light is within the new medium with constant properties, it travels in a straight line again.

  • A pen partially submerged in a bowl of water appears bent due to refraction at the water surface.


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