Presentation on theme: "LIGHT ! from bonfires to lasers. 2 Sources of light Hot objects give out light. A bonfire."— Presentation transcript:
LIGHT ! from bonfires to lasers
2 Sources of light Hot objects give out light. A bonfire
3 The Sun Sunset in Venice
4 Stars Stars and galaxies give out light. Picture: Liverpool Telescope
6 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
7 Some cold things give out light: some fungi glow worms light sticks LEDs ‘glow-in-the-dark’ stickers
8 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 On the look out ! How do you know that the baby squirrel watches as it feeds?
12 Reflection When light bounces off something we say the light is reflected. We can try this with rough surfaces and shiny surfaces.
14 Shiny surfaces Light is reflected as a beam and can be seen on the wall. wall mirror
15 Move the mirror The light reaches a different place on the wall. wall
16 Look in a mirror Light is reflected. You can see a reflection.
17 Change the direction of the light beam Light is still reflected. You see a reflection - in a different direction.
18 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 - - -
19 Now for some games !
21 Sunlight shining on CDs Where do the colours come from?
22 Rainbow red orange yellow green blue indigo violet
23 Colours White light is made up of lots of colours
24 Colours from white light Look at a lamp through the grating. You will see colours.
28 Adding colours with light This is different to adding paints
29 Red + Blue magenta
30 Blue + Green cyan
31 Green + Red yellow
36 Fairy lights
37 Uses Lasers- produce very bright beams of light. The atoms all give out their light together CDs use laser light and reflection-
38 CDs The surface has tiny pits and smooth bits in a spiral pattern the pits scatter light from a laser the smooth bits reflect the light so a coded message is read. spiral