light- Ch14

law of reflection

angle of incidence= angle of reflection

specular reflection

on a smooth surface so rays all reflect at the same angle

diffuse reflection

reflection on a rough or bumpy surface where rays scatter in different directions

refraction

change of direction when the wave crosses boundaries between mediums because of a change in speed of light

image

the point where the light rays appear to come from

white light

produces a spectrum after passing through a prism because different colours refract different amounts

dispersion

the splitting up of white light into spectrum

water is denser than air so light refracts and slows down

water makes an object appear larger because

the colour which is reflected and isn’t absorbed

the colour we see is

what does black absorb?

every colour

what does white absorb?

no colours

real image

formed by focusing light onto a screen, when rays converge

virtual image

image is upright and laterally inverted, where light appears to come from after is has been reflected, when rays diverge

transparent objects

transmit all light, absorb no light

translucent objects

allow light to pass but it is scattered and reflected

opaque objects

absorbs all light that reaches it

magnification=

image height / object height

convex lens

focus parallel rays onto the principle focus

concave lens

makes parallel rays spread out and appear like they are coming from the principle focus

real if it further away from the lens than the principle focus

virtual if the object is nearer to the lens than the principle focus (convex)

concave lenses always produce

virtual images as they make rays spread out

upright or magnified or virtual

inverted or smaller or real