light waves Flashcards
what is the ray hitting a mirror called
incident ray
what is the ray bouncing off a mirror called
reflected ray
what is the line drawn at 90º to a mirror called
the normal
what is the angle of incidence
the angle between the incidence ray and the normal
what is the angle if reflection
the angle between the normal and the reflected ray
what does the law of reflection state
the angle of incidence = the angle of reflection
what is refraction
the bending of a wave (changing direction) as it passes from one medium to another
what happens when light travels from air to glass
- the angle of incidence is greater than the angle of refraction
- the ray beds towards the normal
what happens when light travels from glass into air
- the angle of incidence is smaller than the angle of reaction
- the ray bends away from the normal
why are the wavefronts closer together inside the glass
in the glass the waves are slower
what is the equation for refractive index
refractive index = sin(angle of incidence) / sin(angle of refraction)
what is the symbol equation for refractive index
n = sin i / sin r
what is the definition of critical angle
the angle of incidence that gives the angle of refraction of 90º
what is the equation to find the critical angle
sin(critical angle) = 1/refractive index
what is the symbol equation to find the critical angle
sin c = 1/n
how do we get total internal reflection
when the angle of incidence is greater than the critical angle
what are optical fibres
thin core strand of glass where the light pulses travel
two examples of optical fibres
- endoscope
- telephone communication
