Notes of Light Reflection and refraction class xth
Answers
Reflection is the abrupt change in the direction of propagation of a wave that strikes the boundary between two different media. At least some part of the incoming wave remains in the same medium. Assume the incoming light ray makes an angle θi with the normal of a plane tangent to the boundary. Then the reflected ray makes an angle θr with this normal and lies in the same plane as the incident ray and the normal.
Law of reflection: θi = θr

Specular reflection occurs at smooth, plane boundaries. Then the plane tangent to the boundary is the boundary itself. Reflection at rough, irregular boundaries is diffuse reflection. The smooth surface of a mirror reflects light specularly, while the rough surface of a wall reflects light diffusely. Thereflectivity or reflectance of a surface material is the fraction of energy of the oncoming wave that is reflected by it. The reflectivity of a mirror is close to 1.

Refraction
Refraction is the change in direction of propagation of a wave when the wave passes from one medium into another, and changes its speed. Light waves are refracted when crossing the boundary from one transparent medium into another because the speed of light is different in different media. Assume that light waves encounter the plane surface of a piece of glass after traveling initially through air as shown in the figure to the right.
What happens to the waves as they pass into the glass and continue to travel through the glass? The speed of light in glass or water is less than the speed of light in a vacuum or air. The speed of light in a given substance is v = c/n, where n is the index of refraction of the substance. Typical values for the index of refraction of glass are between 1.5 and 1.6, so the speed of light in glass is approximately two-thirds the speed of light in air. The distance between wave fronts will therefore be shorter in the glass than in air, since the waves travel a smaller distance per period T.
If f is the frequency of the wave and T = 1/f is the period, i.e. the time interval between successive crests passing a fixed point in space, then λ1 = v1T = cT/n1 and λ2 = v2T = cT/n2, or λ1/λ2 = n2/n1.
hope this helps you
please Mark's as brainlist