Anegative test charge experiences a force to the right as a result of an electric field. which is the best conclusion to draw based on this description?

a. the electric field points to the left because the force on a negative charge is opposite to the direction of the field.
b. the electric field points to the right because the force on a negative charge is in the same direction as the field.
c. no conclusion can be drawn because the sign of the charge creating the field is unknown.
d. no conclusion can be drawn because the amount of charge on the test charge is unknown.

A. The electric field points to the left because the force on a negative charge is opposite to the direction of the field.

Explanation:

The electric force exerted on a charge by an electric field is given by:

where

F is the force

q is the charge

E is the electric field

We see that if the charge is negative, q contains a negative sign, so the force F and the electric field E will have opposite signs (which means they have opposite directions). This is due to the fact that the direction of the lines of an electric field shows the direction of the electric force experienced by a positive charge in that electric field: therefore, a negative charge will experience a force into opposite direction.