Question

Suppose you want to determine the electric field in a certain region of space. You have a small object of known charge and an instrument that measures the magnitude and direction of the force exerted on the object by the electric field. (a) The object has a charge of +30.0 mu C and the instrument indicates that the electric force exerted on it is 250 mu N, due east. What are the magnitude and direction of the electric field? E = (b) What are the magnitude and direction of the electric field if the object has a charge of -30.0 mu C and the instrument indicates that the force is 10.0 mu N due west? E =

Answer 1

a) Charge on object, q = 30 micro C = 30*10^-6 C
   Force experienced, F = 25 micro N in east
   so let the electric field be E
   then qE = F
   E = F/q = 25/30 = 0.8333 N/C
   direction , along east direction
b) Charge on object, q = -30 micro C = -30*10^-6 C
   Force experienced, F = 10 micro N, in west
   so let the electric field be E
   then qE = F
   E = F/q = -10/30 = -0.3333 N/C
   so magnitude of E = 0.333 N/C
   direction , along east