Question

If i = angle of incidence and r = angle of refraction, then
the ratio sini/sinr
I. is a constant for a pair of media.
II. is called refractive index of medium 2 with respect to medium 1.
III. is called absolute refractive index of medium 2.
IV. varies with temperature.
(a) I, II and III (b) II, III and IV
(c) I, II and IV (d) I, III and IV

Answer 1

 (c) The ratio of the sine of the angle of incidence to the sine of angle of refraction is constant. Remember that the angles of incidence (i) and refraction (r) are the angles that the incident and its refracted ray make with the normal, respectively. We have, sin i/sin r =n₂₁ ...(i) where, n₂₁ is a constant, called the refractive index of the medium 2 w.r.t. the medium 1. Eq. (i) is the well known Snell’s law of refraction. We note that n₂₁ is a characteristic of the pair of media (and also depends on the wavelength of light) but is independent of the angle of incidence