In this Activity, you will analyze three different cases of a thin film between two materials. Consider what happens when light starts in the top material (e. g. air for Case 1), will light reflecting off of surface A undergo a phase shift, will light reflecting off of surface B undergo a phase shift? Then consider what happens when light starts in the bottom material (e. g. glass for Case 1).

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?