Reflection, Refraction and lenses Flashcards
What is reflection?
It is when a wave is bounced off a surface
What is refraction?
It is the bending of light rays at a surface
Light waves reflect from a shiny surface following the laws of reflection. What are these laws?
The angle of incidence equals the angle of reflection. And the incident ray, reflected ray and the normal are all in the same plane.
Why does refraction occur?
Refraction occurs because the speed of the wave changes as it passes through different materials.
When light travels from a less dense to a more dense material does it get faster or slower and what way does the light ray bend?
It gets slower and the light ray bends towards the normal
When light travels from a more dense to a less dense material does it get faster or slower and what way does the light ray bend?
It gets faster and the light rays bends away from the normal
Describe a converging (convex) lens
it is fatter in the middle
Describe a diverging (concave) lens
it is thinner in the middle
Where are converging lenses used?
Telescopes, cameras, projectors, binoculars and in our eyes
What is the name for the point on where the image is formed?
Principal focus
What is the relationship between the thickness of the lens and the focal length?
The fatter the lens the shorter the focal length
When creating an image what does the word inverted mean?
Upside down
When creating an image what does the word diminished mean?
Smaller
When creating an image what does the word real mean?
That the image can be projected onto a screen
What types of image can a converging lens create?
Both magnified and diminished. This depends on the position of the object
When the distance between the object and the lens is greater than 2f what will the image be?
Inverted, real and diminished
When the distance between the object and the lens is between f and 2f what will the image be?
real and magnified
When the object is closer to the lens than the focal length, what will the image be?
virtual, upright and magnified
What types of lenses did early telescopes use?
They had a converging lens at the front (objective lens) and a diverging lens to look through (eyepiece)
Why is the image formed sometimes blurred and how could a clearer image be formed?
Because the different colours of light have different focal points and you could make the image sharper by using a concave mirror instead of the objective lens
What types of lenses are there in a modern refracting telescope?
Both the objective and eyepiece lens are converging. The objective lens produces the image and the eyepiece lens magnifies it.
What types of lenses are there in a modern reflecting telescope?
A large concave mirror, a plane mirror and a converging lens. The concave mirror forms the image which is then reflected towards the eyepiece using the plane mirror
