Refraction At A Plane Surface

Question 1

Define: refracted ray, angle of incidence and angle of refraction

Answer 1

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.

Question 2

Laws of refraction

Answer 2

Law 1: The incident ray, reflected ray and normal all lie in the same place.

Law 2: the ration of the sine of the angle of incidence and sine of the angle of refraction is constant.

Question 3

Relative refractive index and absolute refractive index

Answer 3

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.

Question 4

Snell’s Law

Answer 4

Tells us about the relationship between the angle of incidence (i) and the angle of refraction (i’) within a medium.

n sin i = n’ sin i’

Question 5

Define critical angle

Answer 5

The critical angle is the angle of incidence where the angle of refraction is 90degrees. The light must travel from an optically more dense medium to an optically less dense medium.

Question 6

Define total internal reflection

Answer 6

Occurs if the angle of incidence is greater than the critical angle going from a more dense medium to a less dense medium.

Question 7

Explain: prism, principal section of prism, refracting faces and apical angle

Answer 7

Prism: transparent object (shape of prism) that can bend light and separate white light into component colours.

Principal 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 which the refracting faces meet.

Question 8

Deviation in a prism (given apical angle)

Answer 8

d = i1 + i2 - a

Question 9

Apical angle with angle of incidence and angle of refraction

Answer 9

a = i1 + i2

Question 10

Define minimum deviation within a prism

Answer 10

Minimum deviation occurs when the incident angles and the emergent angles are equal.
Only one internal ray parallel to base.

i1 - i2’
i1 - i2’ = a/2
d1 - d2

Question 11

Minimum deviation formula

Answer 11

D min = a/2 = i1’ = i2 then snells law to calculate i1 and i2’

Question 12

Formula to work out i2 in thick prism (given apical)

Answer 12

i2 = A - i1’

Question 13

Critical angle formula

Answer 13

Sin ic = n’/n