A proton moving along the positive x-axis enters an electric field that is directed along the positive y-axis. What is the direction of the electric force acting on the proton after it enters the electric field?

Direction of the electric force acting on the proton after it enters the electric field is along the positive y-axis.

Explanation:

In an electrical field electrical field lines goes from positive to negative. Therefore, electrical force vector is on exactly the same way with electrical field lines for a proton. Which means if the electrical field directed along the positive y-axis, electrical force for proton will be on the same way.