Which gas in earths atmosphere protects earth by reflecting ultraviolet radiation

Four objects each with charge +2.0×10−7c are located at the corners of a square whose sides are 2.0 m long. part a what quantities can be determined using this information? check all that apply. the electric force on a charged object placed at the center of the square. the mass of each object. the total electric potential energy of the system consisting of the four charged objects. part b find the electric force on a charged object placed at the center of the square.

How much work would it take to move a coulomb charge across a 4 volt potential difference?

2) the sun is wonderful source of energy. it is renewable and natural with few dangers. solar cells rely on the sun for energy. these cells would be more practical to use if they were