Light Flashcards
(19 cards)
Energy
Is the ability to do work ie. move. The unit of energy is the joule.
Plants
Use light to make food (photosynthesis).
Humans
Use light for solar panels and Crooke’s radiometer.
Luminous
Objects that give off light are called luminous objects eg. the sun, lightbulb, candle.
Non-luminous
Objects that do not give off light, and need light to bounce off them for us to see are called non-luminous eg. a book, faces, a table.
Light
Is a form of energy.
Light travels in straight lines
We can show this by blocking light from a bulb with card.
Light does not travel around corners
Blocking light leads to shadows.
A solar eclipse
Occurs when the moon passes between the sun and the earth.
A lunar eclipse
Occurs when the earth is between the sun and the moon, the moon is in the earth’s shadow.
Reflection of light
Occurs when it bounces off a surface.
Regular reflection
Shiny, smooth surface (mirror) the rays are reflected back at the same angle.
Irregular reflection
Rough surface (ball of tinfoil).
Concave or diverging mirrors
Telescopes, make up and shaving. Can enlarge the image.
Convex or converging mirrors
Side mirror in cars, security mirrors in shops. Small, upright image with a wider field of vision.
Refraction
The bending of light as it goes from one medium to another eg. air to water. Light rays are refracted towards the denser material.
Convex or converging lens
Used to bring rays together. Used to fix long sightedness, or hypermetropia.
Concave or diverging lens
Used to spread rays apart. Used to fix short sightedness, or myopia.
White light
White light is not really white. It is a mixture of the 7 colours of the spectrum.
