Consider a square which is 1.0 m on a side. Charges are placed at the corners (m
ID: 2044536 • Letter: C
Question
Consider a square which is 1.0 m on a side. Charges are placed at the corners (marked A,B,C D) of the square as shown in the figure. Q = 5 µC and q = 2 µC (NOTE: -q = -2 µC).
(a) Which is the magnitude and direction of the electric field at the center of the square?
Magnitude N/C
direction
(b) What is the electric potential at the center of the square? V
(c) If a -2 µC charge is placed at the center what is the magnitude and direction of the electrostatic force active on the negative charge?
Magnitude N
direction
(d) If a -2 µC charge is placed at the center, how much work (positive or negative) would you have to do to remove it to infinity? J
Explanation / Answer
A) The electric field at the center is zero due to the sum of the vectors. You place a positive point charge at the center and the symmetry and equal charges makes it zero. The electric potential at the center is equal to V= 4kq/r because of the 4 point charges. Voltage is scalar so you don't need to worry about direction, just sum the voltages. r = sqrt(2)/2, q = Q, k = 9*10^9.