Two waves A and B of frequencies 2 MHz and 3 MHz, respectively are beamed in the same direction for communication via sky wave. Which one of these is likely to travel longer distance in the ionosphere before suffering total internal reflection?

Question

Two waves A and B of frequencies 2 MHz and 3 MHz, respectively are beamed in the same direction for communication via sky wave. Which one of these is likely to travel longer distance in the ionosphere before suffering total internal reflection?

Philoid · Accepted Answer

The extent of refraction of the light wave in a medium for a light wave with larger frequency is greater. Hence, B (blue line) will go through more bending. The greater the refraction, the more the bending. Hence, B will reach the critical angle first and go through total internal reflection. Thus, A (yellow line) will travel longer distance.