Lenses Flashcards
What is a lens?
Shaped piece of transparent glass or plastic that reflects light
What happens when light is refracted?
It changes direction due to the change in density as it moves from air to glass or plastic
Where are lenses used?
Cameras
Telescopes
Binoculars
Microscopes
Corrective glasses
What does a concave lens look like?
Thinner in the middle then the edges
What do light rays do in convex lenses?
Parallel light rays enter the lens and converge
They come together at a point called the principle focus
How are convex lenses drawn in ray diagrams?
They are drawn as a vertical line with outwards facing arrows to indicate shape of the lens
What is focal length ?
Distance from lens to principle focus
What do concave lenses look like?
Thinner in the middle than the edges
What happens to light rays in a concave lens?
Parallel rays diverge
They separate but appear to come from behind a principle focus on the other side of the lens
How are concave lenses drawn in ray diagrams?
It’s drawn as a vertical line with inwards facing arrows to indicate shape of the lens
What can images formed by a lens be?
Upright or inverted
Magnified or diminished
Real or virtual
What is a real image?
Image that can be projected onto a screen
What is a virtual image?
Image appears to come from behind the lens
What are light rays in virtual images like?
Rays of light appear to come but do not so in reality
What devices contain convex lenses?
Cameras and eyes