Light Lesson 1

LIGHT LIGHT –– Lesson 1 Lesson 1

Targets 1. To know that light is a form of

energy which travels away from a source in straight line

2. To learn that light travels at a very high speed

Making lightMaking light

Light needs an energy source to be created.

Once created it travels at high speed (3 000 000 metres per second) away from the source

Sources of lightSources of light

Natural sources Sun. Moon (reflected

sunlight). Burning wood. Lightning Stars

Artificial sources

Candles. Lamps. Flashlight

bulbs. TV. Projector

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.

How fast does light really How fast does light really traveltravel Across a field in

less than one millionth of a second.

From the Moon in 1.3 seconds

From the Sun in 8 minutes

From the nearest star in 4 years

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

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

Light travels in straight

lines.

Light travels in straight Light travels in straight lineslines

Three screens experiment shows that this is true

Light travels in straight Light travels in straight lineslines

Three screens experiment shows that this is true

Amazing factAmazing fact

To see light you have to destroy it, once it enters your eye it does not come out but is absorbed by the cells on the retina!

ShadowsShadows

Copy the diagram and draw lines to show how a shadow is formed