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Worksheet: Calculating the Net Electric Field of Multiple Point Charges

Q1:

Two equal sized charged spheres, Sphere A and Sphere B have charges of + π‘ž 1 and βˆ’ π‘ž 2 respectively. The spheres are separated by a straight-line distance 𝑑 . The net electric field produced by spheres has a null point along 𝑑 at a distance of 𝑑 4 m from Sphere A. What is the ratio of the magnitude of the charge of Sphere B to that of Sphere A?

  • A π‘ž 2 = 3 π‘ž 1
  • B π‘ž 2 = 2 π‘ž 1
  • C π‘ž 2 = 4 π‘ž 1
  • D π‘ž 2 = 9 π‘ž 1
  • E π‘ž 2 = 8 π‘ž 1

Q2:

Two fixed charges of +30 mC and βˆ’15 mC, respectively, are separated horizontally by a distance of 12.0 cm. Four points of interest, 𝑃 1 , 𝑃 2 , 𝑃 3 , and 𝑃 4 , have positions relative to the fixed charges, as shown in the diagram.

Find the net potential due to the charges at 𝑃 1 .

Find the net potential due to the charges at 𝑃 2 .

Find the net potential due to the charges at 𝑃 3 .

Find the net potential due to the charges at 𝑃 4 .

Q3:

Point charges are placed at the four corners of a rectangle as shown. The charges’ magnitudes are: What is the electric field in the plane of the rectangle at the point 𝑃 ?