. a. A ray of light enters a fiber optic cable with index of refraction n from air at an angle as shown below. Let the angle 0 be 69°. For total internal reflection to occur at the cable- air interface, what must be the value of n? n=1.3 nair = 1 Bd OR 8 n Think & Prepare You have three unkowns in this problem, the angle of refraction R, the angle of refraction and n. 1. Set-up Snell's Law equation relating 6, R, and n. 2. Set-up the critical angle relationship between cand n 3.0+0=? sine 4. You may need some trigonometric identities such as sin (90° - 0) = ? and = 2. cose b. In the problem above, the angle e increases. How does this affect what n must be to ensure total internal reflection? A) n will decrease because the critical angle will become larger B) n will decrease becuase the equation for the critical angle is proportional to 1/n of the material C) n will increase because the critical angle will become smaller D) n will increase becuase the equation for the critical angle is proportional to 1/n of the material ○ A AB O CD AC BD No, that's only partially correct