Question

 

1) A point charge is placed at each comer of a square with side length a. The charges all have the same magnitude q. Two of the charges are positive and two are negative, as shown in the following figure.

 

Part A

What is the direction of the net electric field at the center of the square?

a) leftward direction
	b) upward direction
	c) rightward direction
	d) downward direction

Part   B

  

What is the magnitude of the net electric field at the center of the square due to the four charges in terms of q and a ?

  

Express your answer in terms of the variables q, a, and appropriate constants.