State the fundamental laws on which ray optics is based.

Ray optics is based on the following fundamental laws:

i. Light travels in a straight line in a homogeneous and isotropic medium.

ii. Two or more rays can intersect at a point without affecting their paths beyond that point.

iii. Laws of reflection:

a. Reflected ray lies in the plane formed by incident ray and the normal drawn at the point of incidence and the two rays are on either side of the normal.

b. Angles of incidence and reflection are equal (i = r).

iv. Laws of refraction:

a. Refracted ray lies in the plane formed by incident ray and the normal drawn at the point of incidence; and the two rays are on either side of the normal.

b. Angle of incidence (90 and angle of refraction (62) are related by Snell’s law, given by,

n₁ sin θ₁ = n₂ sin θ₂

where, n₁, n₂ = refractive indices of medium 1 and medium 2 respectively.