The angle of refraction is 15.6 deg.
When a ray of light passes from medium 1 to medium 2, the refractive index of medium 2 with respect to 1 is the ratio of the absolute refractive index of medium 2 and medium 1

When light passes from air into diamond, with the given values of refractive indices,

According to Snell's law,

The angle of refraction is 15.6 deg
We are given the gravitational potential energy and the height of the ball and is asked in the problem to determine the mass of the ball. the formula to be followed is PE = mgh where g is the gravitational acceleration equal to 9.81 m/s^2. substituting, 58.8 J = m*9.8 m/s^2 * 30 m; m = 0.2 kg.
A light year is a distance.
It's the distance that light travels in a year, through vacuum.
The distance is about 5.875 trillion miles.
The nearest star outside our solar system is about 4.2 light years from us.
Sorry to have rambled on for so long.
Answer:
C. Yes because the hang glider is moving.
Red light would be commonly used due to the longer wavelength