can you give me more detail explanation?

Example 8 The refractive index for the glass prism shown below is 1.55. In order for a beam of light to experience total internal reflection at the right-hand face of the prism, the angle 0, must be smaller than what value? 60 normal normal 01 incident total internal beam reflection occurs here glass prism 360 0 Solution. Total internal reflection will occur at the glass/air boundary if 0, is greater than the critical angle, 0, which we can calculate this way: sin 0 = hair 0 = 40 03+01= 60" n glass 1.55 Because , = 60 - 0,, total internal reflection will take place if 0, is smaller than 20. Now, by Snell's Law, 0, = 20 if "air Sin 01 = n glass sin 02 sin 0, = 1.55 sin 20 0 = 320 than 320. Therefore, total internal reflection will occur at the right-hand face of the prism if 0, is smaller