Light Flashcards
What are light sources?
A light source is anything that makes light, whether natural and artificial.
What is infrared radiation/thermal energy?
It is very similar to light and is another way by which energy reaches us from the sun.
What are shadows?
Shadows are dark areas where something blocks our light.
What is a penumbra?
The Penumbra is a half-shadow region that occurs when a light source is only partly covered by an object.
What is an umbra?
The innermost and darkest part of a shadow, where the light source is completely blocked by the occluding body.
How fast is the speed of light?
The speed of light is 300 000 km/s
What is a permanent magnet?
A piece of iron or steel that has been magnetised is a permanent magnet.
How can you demagnetise a magnet?
You can demagnetise a magnet by heating it up or hitting it with a hammer.
What is a magnetic field?
The area around the magnet in which the forces of attraction and repulsion can be felt.
What is an electromagnet?
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current.
