A +20-nC point charge is placed on the x axis at x = 2.0 m, and a −25-nC point charge is placed on the y axis at y = −3.0 m. What is the direction of the electric field at the origin?
A) 209°
B) 61°
C) 29°
D) 241°
E) 151°

Question

Quizplus · Accepted Answer

The electric field direction at the origin due to a point charge is along the line connecting the charge and the point of interest. For the +20-nC charge at (2.0 m, 0), the electric field at the origin points towards the charge (since it's positive), along the positive x-axis. For the -25-nC charge at (0, -3.0 m), the electric field at the origin points away from the charge (since it's negative), along the negative y-axis. The angle of the resultant electric field vector can be found using the arctan of the ratio of the y-component to the x-component of the electric field. Given the symmetry and the quadrant, the correct angle with respect to the positive x-axis is 209°, which accounts for the electric field directions and the positions of the charges.

A +20-NC Point Charge Is Placed on the X Axis