p5.3 Flashcards
what are ray diagrams
these show how light is reflected or refracted
why are electromagnetic waves refracted
when light or other waves slow down the bend towards the normal. the denser the object its passing through the more it bends
where is refraction / reflection of electromagnetic waves used
the earth is curved so when sending electromagnetic signals very long distances the waves have to be reflected of of a layer of atmosphere called the ionosphere.
how does the wavelength affect the what happens to a wave
the different waves are effected very differently by different objects. eg a wall will let radio and microwaves pass through it but it will not let light waves pass through.
or a bin bag wont let light in but will allow infrared through
whats the difference between a convex and concave lens
convex = refracts light to a single focal point (converging) concave = causes the light that passes through it to spread out. (diverging)
what is long and shortsightedness, what causes it, how do you fix it
longsightedness = things close to you seem blurry. this is because the light rays cross behind the retina. fix with a concave lens.
shortsightedness = things at a distant seem blurry. this is because the light ray cross over before the retina. fix with a convex lens.
how do you produce a spectrum of white light
by using a glass prism. when light passes through it each colour travels at a slightly different speed and is refracted slightly differently. the colours all spread out due to there different frequencies
what are the spectral colours
the colours associated with the frequencies within the colour white
what is it called when the colours of white light spreads out
dispersion
what colours are our retinas sensitive to? why can we see more colours than just those colours.
the retina is sensitive to red, blue and green. these colour send electrical signals to the brain to create perceived colours
how is colour related to absorption and tramsitting
if a white light is placed behind a red filter the filter will only allow red light to pass through it whilst absorbing everything else.
what are the two types of reflection
specualr/regular = reflection off a flat surface eg mirror
scattered / diffuse = reflection off of a surface that isn’t flat
why is the sky blue
because the small air particles scatter the light waves with short wave lengths such as blue
