JAMB - Physics (1985 - No. 31)
Two rays of light from a point below the surface of water are equally inclined to each other at 60o in water. What is the angle between the rays when they emerge into air? (Take the refractive index of water to be \(\frac{4}{3}\))
41.8o
44.1o
60.0o
83.6o
120.0o
Explanation
\(\frac{4}{3}\) = \(\frac{sin r_1}{sin 30}\) and \(\frac{4}{3}\) = \(\frac{sin r_2}{sin 30}\)
r1 = 41.8o and r2 = 41.8o
angle between them = r1 + r2
= 83.6o
r1 = 41.8o and r2 = 41.8o
angle between them = r1 + r2
= 83.6o