Light

Features of Light

• Light travels at 300 000 000 m/s, one million times faster than sound.  This is why you see lightning before you hear it.
• Light travels in straight lines.
• Cannot travel through opaque materials.  This is when shadows form.  One side of the opaque object is lit up but as light cannot travel through or around it, a shadow is formed on the other side.
• Light rays are emitted from luminous sources, the moon is not one of these!

Reflection

• When light rays hit a surface, they bounce off again.  This is reflection.
• Smooth surfaces like mirrors reflect light in the same direction whereas rough surfaces light a wooden table reflect light in lots of different directions.

How Plane (Flat) Mirrors Reflect Light

• The normal is an imaginary line at 90 degrees to the mirrors surface.
• The angle of incidence is the angle at which light rays being emitted from the light source hit the mirror, these are called incident rays.
• The angle of reflection is the angle at which rays bounce back off the mirror.  These are called reflected rays.

The Angle of Incidence = The Angle of Reflection

Refraction

• When light travels into a different medium to air, such as water or glass, it slows down and bends.
• This can make things seem to be in a different position to what they really are.  This is refraction.