1. which three components would you find in any modern system for gathering radiation from
astronomical sources such as stars and galaxies?

The speed of light in a material is 0.50 c. what is the critical angle of a light ray at the interface between the material and a vacuum?

Which safety measures should you follow during a thunderstorm? check all that apply. (a) avoid touching anything that conducts electricity. (b) avoid touching a person who has been struck by lightning. (c) go outside. (d) keep your computer turned off. (e) stay out of water. (f) stay inside.

The coefficient of friction is a number that represents the resistance to sliding between two in contact with one another.