13. When a single charge q is placed on one corner of a square,the electric field at the center of the square is F/q. If threeother equal charges are placed on the other corners, the electricfield at the center of the square due to these four equal chargesis
A) F/(2q). B) F/(4q). C) 4F/q. D) F/q. E) None of the choicesare correct.
14. Lightning (a flow of electrons between the ground and athundercloud) lasts about 120µs. The rate of charge flow in atypical lightning bolt is about 25,000 coulombs per second.
A) How much total charge flows between the ground and the cloudduring a typical lightning bolt?
B) How many electrons flow during this time?
