P5 | EM spectrum Flashcards
laws of reflection
- the incident ray, reflected ray and normal all lie on the same plane
- angle of incidence ALWAYS = angle of reflection
- reflected ray and incident ray are on the opposite sides of the normal
when does specular reflection occur?
when parallel EM waves are reflected in a single direction by a smooth surface
when does diffuse reflection occur?
when parallel EM waves are scattered by a rough surface
what is the critical angle?
the angle at which light refracts along the boundary (where the angle of refraction is 90°)
when does refraction occur?
when the angle of incidence is less than the critical angle
when does refraction along the boundary (at 90°) occur?
when the angle of incidence is equal to the critical angle
when does total internal reflection occur?
when the angle of incidence is greater than the critical angle
what is white light?
all the wavelengths of the visible spectrum at equal intensity
why do we see clothes as certain colours?
- dye molecules in fabric absorb all the wavelengths of light in “white light”
- the dye molecules only transmit/reflect the wavelengths corresponding to the colour they are (e.g. red dyes only emit red wavelengths)
what is a colour filter?
a sheet of transparent material that only transmits certain wavelengths of visible light
other name for a concave lens
diverging lens
other name for a convex lens
converging lens
how many times is light refracted in a convex lens?
twice
what is the focal point?
the point where the light converges on the principle axis
what is the focal length?
the distance between the focal point and the centre of the lens
