P14 lenses (paper 2) Flashcards
what type of images are always formed from a concave lense
virtual
what are the two types of lense
- convex
- concave
what lense is the one which seperates light rays
concave
what are the two types of reflection
- diffuse
- specular
what is diffuse reflection
when light is reflected in all directions from rough surfaces
what is specular reflection
when light is refleccted in one direction off of a smooth surface
what should you do to find the prosition of an object with a mirror
- draw a ray from object & reflect
- draw another ray & reflect
- extrapolate both rays
- image is formed where line cross
what are the two types of images
- virtual
- real
what are the two sizes of images
- magnified
- diminished
what are the two ways of images
- upright
- inverted
what are the other names of a convex and concave lense
- converging
- diverging
what is the focal length
the distance from the center of a lens to the point where light rays parallel to the principal axis are focused.
where is the principal focus of a convex image
where the rays all meet after hitting the lens parallel to the axis
where is the principle focus of a concave image
where the rays hitting the lens parallel to the axis appear to all come from
what are the rules when refraction in a convex lense
- parallel ray goes straight then through focal point
- central ray goes straight through centre of lense
- image is formed where the lines cross (real or virtual)
what are the rules when refraction in a concave lense
- parallel ray goes forward to hit lense ~ extreoplate back
- centeral ray goes through focal point infront of lense
- image is forced where lines cross
how do you calculate magnification
magnification = image height / object height
what is the law of reflection
angle of incidence = angle of reflection
define a real image
An image formed by a lens that can be projected on a screen.
define a virtual image
An image, seen in a lens or a mirror, from which light rays appear to come after being refracted by a lens or reflected by a mirror.
describe refraction
Refraction is where light changes direction when it enters a new material.
why does refraction happen
becuase light rays change speed when entering a new material and bend either towards or away from the normal
when velocity of a light ray decreases what happens to the wavelength
the wavelength decreases
describe a translucent object
an object that allows light to pass through, but the light is scattered or refracted
