Light Flashcards
What is the angle of incident equal to?
The angle of reflection
What is total internal reflection? (TIR)
When no light passes from the glass into the air
What is the critical angle for TIR?
42°
What is refraction?
When no light passes from one medium to another
What changed during refraction?
The speed of light, usually changed direction
What happens when light enters a more dense material?
It slows down
What happens when light enters a less dense material?
It speeds up
What is an example of refraction going to one medium to another?
Air to glass
Glass to air
What is the normal?
The point which is at a right angle to the surface
What would happen is light was to travel through air to glass?
It would slow down because it is entering a more dense material
What is white light made up from?
Red, orange, yellow, green, blue, indigo and violet (the colours of the rainbow)
When do all the individual colours of the rainbow show?
When white light refracts
Describe application
When light from the sun appears white, but is refracted through water droplets in the atmosphere, you can see the colours of the rainbow
What are the primary colours of light?
Red, green and blue
What is dispersion?
When a prism splits a ray of white light into all the colours of the rainbow
What colour is most refracted?
Violet (think ULTRA violet)
What light is least refracted?
Red light
How many colours can light be split into?
7
What splits colours?
Prisms
What do lenses do?
Reflect parallel beams of light so that they bend away or towards each other
What are the two main types of lenses?
Convex and concave
What does a concave do to the rays?
It makes them spread out
What are pupils?
Basically holes in our eyes that allow in light, the size and diameter change depending on the light levels
In humans, where does light enter?
Through the cornea and pupils
How does the brain receive images?
By the cornea and the lens focusing light onto the retina and the optic nerve carries the information to the brain
What happens when we look at an object close up?
The lens becomes fatter, more powerful
What happens when we look at a distant object?
The lens becomes thinner, less powerful
A converging lens = ?
A positive focal point and a positive power
A diverging lens = ?
A negative focal point and a negative power
Do convex lenses have a positive or negative effect?
Positive
How do we measure the focal length of a convex lens?
We measure between the normal and the focal point
