Light

What is Light?

• Light is composed of particles called photons which are massless bundles of concentrated electromagnetic energy and the travel in waves. Transverse Waves

Properties of Light

• Light travels in straight lines:

Laser

• Light travels VERY FAST – around 300,000 kilometres per second.

At this speed it can go around the world 8 times in one second.

A light-year is the distance light travels in one year and is a unit of measure.

• Light travels much faster than sound. For example:

1) Thunder and lightning start at the same time, but we will see the lightning first.

2) When a starting pistol is fired we see the smoke first and then hear the bang.

Electromagnetic

• Electromagnetic waves- is energy traveling in a wave that is partially electric and partially magnetic.

• Electromagnetic Spectrum- all the electromagnetic waves that reach earth.

Electromagnetic Spectrum

• Radio, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays

• Organized from longest wavelength to shortest

• We have various uses for each type of wave

Color

• White light is not a single color; it is made up of a mixture of the seven colors of the rainbow.

We can demonstrate this by splitting white light with a prism:

This is how rainbows are formed: sunlight is “split up” by raindrops.

The colors of the rainbow:(ROY G BIV)

• Red

Orange

• Yellow

• Green

• Blue

• Indigo

• Violet

Objects and Light

• Transparent Objects- visible light can pass through them. Example: Clear glass

• Opaque Objects- No light passes through them . Example wood, bricks etc.

• Translucent Object- some light passed through . Example: Frosted Glass

• ShadowsA shadow is formed where light can’t reach.The larger the light source the larger the shadow.

Shadows are places where light is “blocked”:

Rays of light

Polarization

• Light waves are transverse and that means they can be polarized-when waves travel in one direction.

Polarized lenses filter light and caused it to be polarized reducing glare.