Electric Fields and Point Charges

[PrideofPhilly]

Homework Statement

Suppose you want to determine the electric field in a certain region of space. You have a small object of known charge, and in an instrument that measures magnitude and direction of the force exerted by object by the field.

(a) The object has a charge of +20.0 C, and the electric force exerted on it is 40.0 N due east. What are the magnitude and direction of the electric field?

(b) What are the magnitude and direction if it has a charge of -10.0 C and the force 20.0 N due west?

Homework Equations

E = F/q0

The Attempt at a Solution

(a) E = 40.0 N/20.0 C = 2.00 N/C due east

(b) E = -20.0 N/-10.0 C = 2.00 N/C due east

Are these the right magnitudes and directions?

 

[jgens]

Looks pretty good to me.

 

[nlightner]

Yes, these are the correct magnitudes and directions for the electric field in both cases. The electric field is a vector quantity, meaning it has both magnitude and direction. The magnitude of the electric field is determined by dividing the force by the charge of the object, and the direction of the electric field is the same as the direction of the force exerted on the object. In the first case, the force and the electric field are both pointing east, and in the second case, they are both pointing west. This aligns with the fact that like charges repel and opposite charges attract, resulting in the direction of the electric field being dependent on the charge of the object.