Question

1. f the refractive index of glass is 1.5, what is the critical angle at the air-glass
interface?                                                                                                                                   (5 marks)
2. A man wears convex lens glasses of focal length 30 cm in order to correct his
eye defect. Instead of the optimum 25 cm, his least distance of distinct vision is
what?                                                                                                                                          (5 marks)
3. A man hears his echo from a nearby his 2 seconds after he shouted. If the
Frequency of his voice is 260Hz and the wavelength is 1.29 m, how far is the hill?    (5 marks)

Answer 1

1. The critical angle can be found as follows:-

Answer - Given that refractive index of glass= 1.5 The critical angle is that angle at which, if a ray is incident white passing from an optically dense to optically rare medium, the angle of refraction is goo .. According to shell's law Sin sini. M2 sinr Mi sinler - (2= | since Mairit) singo' 1.5 sin ior-15 lor- sint (!) ler sint (0.67) lcr= 42.06 critical angle is So the 42.06°.