Model a parabolic GRIN fiber by the equivalent multiple-step approximation.
Let n1=1.5, Δ=0.01. Divide the radius into 10 equal parts. Consider a ray crossing the fiber axis at 5° with respect to that axis (and inside the fiber). Sketch its progress through the fiber until it turns back and re-crosses the fiber axis. (The angles can be magnified on your sketch.)
At what value of r/a did the ray turn back by total reflection?

i dont know but

explanation:

whoever your teacher is, deserves a raise for using pokemon as an example

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.

frequency or wavelenth of em radiation in a vacuum