Refraction at a plane surface Flashcards
Define:
Refracted ray
Angle of incidence
Angle of refraction
Refracted ray - is a ray of light travelling from one medium to another and changing direction.
Angle of incidence - angle between the incident ray and the normal
Angle of refraction - angle between the normal and the refracted ray
Laws of Refraction
Law 1: The incident ray, reflected ray and the normal lie in the same plane.
Law 2: The ratio of the sine of the angle of incidence and sine of the angle of refraction is constant.
Relative refractive index
Absolute refractive indx
Relative - Is the speed of light from one medium to another
Absolute - the ratio of the speed of light in vacuum and in the given medium.
Snell’s Law
n sin i = n’ sin i’
Define critical angle
The critical angle is the angle of incidence where the angle of refraction is 90°. The light must travel from an optically more dense medium to an optically less dense medium.
Define total internal reflection
Occurs if the angle of incidence is greater than the critical angle going from a more dense medium to a less dense medium.
Explain:
Prism
Principle Section of prism
Refracting faces
Apical Angle
prism - transparent object (shape of prism) that can bend light and seperate white light into component colours.
Principle section of prism - front facing, triangular section of prism
Refracting faces - two plane faces angle towards each other, meeting at the top
Apical angle - is the angle opposite the base in which the refracting faces meet
Deviation in a prism (given apical angle)
d = i1 + i’2 - a
Apical angle with angle of incidence and angle of refraction
a = i1 + i’2
Define minimum deviation within a prism
Minimum deviation occurs when the incident angles and the emergent angles are equal
Only time internal ray parellel to base
i1 - 12’
i1 - 12’ = a/2
d1 - d2
Minimum deviation formula
D min = a/2 = i1’ = 12
Formula to work out i2 in thicc prism (given apical)
i2 = A - i1’
Critical Angle formula
Sin ic = n’/n
