LIGHT from bonfires to lasers Sources of light

LIGHT ! from bonfires to lasers

Sources of light A bonfire • Hot objects give out light. 2

The Sun • Sunset in Venice 3

Stars • Stars and galaxies give out light. Picture: Liverpool Telescope 4

Lightning 5

A worm living in dark caves sends out light from its tail. • Liquid droplets form a string of shining beads to attract insects. tail of worm 6

Some cold things give out light: • some fungi • glow worms • light sticks • LEDs • ‘glow-in-the-dark’ stickers 7

Task • List all of the sources of light you can find or see (can you think of any additional light sources you can’t see at the moment). • Split these light sources into natural light and man-made sources of light. • How many can you think of?

How do we see light sources? • Light travels from a source to our eyes. • We can see sources in a dark room. 9

Can we see in the dark? • If there is no light • we cannot see anything! • Let’s try a test– • Put a few small objects into the black bag----- 10

How do we see things that are not sources of light? • Light bounces off and some reaches our eyes. 11

Reflection • When light bounces off something • we say the light is reflected. • We can try this with • rough surfaces • and shiny surfaces. 12

Shiny surfaces wall mirror Light is reflected as a beam and can be seen on the wall. 13

Move the mirror wall The light reaches a different place on the wall. 14

Look in a mirror • Light is reflected. • You can see a reflection. 15

Change the direction of the light beam • Light is still reflected. • You see a reflection in a different direction. 16

Multiple reflections • The lamp hangs between two large mirrors on opposite walls. • The reflection in the first mirror is reflected in the second mirror, which is reflected again in the first mirror --17