1. Shadows
D. Crowley, 2008

2. Shadows
To know how shadows are formed

3. Light What is light? How does it travel, and at what speed?
How can we see objects?
Do all objects give out light?
Discuss what you know about light with your partner…

4. Light Light carries energy and travels as a wave
Light travels extremely quickly - 300,000 km/s (much faster than sound - think about fireworks / thunderstorms)
Light waves travel in straight lines (it cannot bend around corners)

5. Shadows Why do shadows form?
Light travels in straight lines (it cannot bend around corners)
Shadows form because light cannot bend round behind an object

6. Luminous Some objects are known as luminous
A luminous object gives out light (a light source), such as: -
Fires
Light bulbs
Stars (e.g. the Sun)

7. Luminous How does light travel from a luminous object to our eye?
Light travels in a straight line, directly to your eye

8. Non-luminous Most objects are non-luminous
A non-luminous object does not give out light
We see non-luminous objects by light from a luminous object hitting the non-luminous object and reflecting into our eye

9. Non-luminous
How does light travel from a non-luminous object to our eye?
Light from the luminous object hits the non-luminous object, reflecting light into our eye

10. Terms
Opaque - materials which do not allow light to pass through them (e.g. a brick wall)
Transparent - materials which do allow light to pass through them (e.g. a glass window)
Translucent - materials which only allow part of the light to pass through them (e.g. paper)

11. Casting Shadows
Complete the casting shadows worksheet

12. Casting Shadows
Shadow of full milk bottle is much bigger, as no light is passing through (opaque)
Drinking class is transparent, allowing light through (so shadow is just an outline, unlike the full shadow of the opaque mug)
Empty cola bottle has only an outline shadow, unlike the full shadow of the full cola bottle
If the lamp is raised the shadows become smaller
If the lamp is lowered the shadows become bigger