Four protons (shown in red) are at the corners of a square, as shown. Which of the following statements best describes the electric field at the centre of the square? a. The electric field points to the right. b. The electric field points to the left. c. The electric field is zero. d. The electric field points towards the upper-right corner.

Four protons (shown in red) are at the corners of a square, as shown. Which of the following statements best describes the electric field at the centre of the square? a. The electric field points to the right. b. The electric field points to the left. c. The electric field is zero. d. The electric field points towards the upper-right corner.