Coulomb’s law & electric fields worksheet with answers

Free printable Coulomb’s law & electric fields worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
++1 µC−−10 µCr = 2 cm

Two point charges of +1 µC and −10 µC are 2 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +1 µCq2 = −10 µCr = 2 cm
F = N
2.Easy
−−5 µC−−1 µCr = 8 cm

Two point charges of −5 µC and −1 µC are 8 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = −5 µCq2 = −1 µCr = 8 cm
F = N
3.Medium
++1 µC−−3 µCr = 25 cm

Two identical small metal spheres carry charges of +1 µC and −3 µC. They are touched together and then put back 25 cm apart. Find the magnitude of the force F between them now. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +1 µCq2 = −3 µCr = 25 cm
F = N
4.Medium
−−2 µC++1 µCr = 20 cm

Two identical small metal spheres carry charges of −2 µC and +1 µC. They are touched together and then put back 20 cm apart. Find the magnitude of the force F between them now. Use k = 8.99 × 10⁹ N·m²/C².

q1 = −2 µCq2 = +1 µCr = 20 cm
F = N
5.Hard
8 cm6 cm+q1​ = +6 µC+q3​ = +2 µC+q2​ = +8 µC

Three positive point charges sit at the corners of a right triangle: q₃ = 2 µC is at the right-angle corner, q₁ = 6 µC is 8 cm from it along one side and q₂ = 8 µC is 6 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 6 µCq2 = 8 µCq3 = 2 µCr13 = 8 cmr23 = 6 cm
F = N
6.Hard
+−P2 × 6 cm6 cm+1 µC−1 µC

Charges of +1 µC and −1 µC are 12 cm apart. Point P lies 6 cm from the midpoint between them, on the perpendicular bisector. Find the magnitude of the electric field E at P. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +1 µCq2 = −1 µCd = 12 cmh = 6 cm
E = N/C

Answer key

  1. 1. F = 224.7 N
  2. 2. F = 7.023 N
  3. 3. F = 0.1438 N
  4. 4. F = 0.05619 N
  5. 5. F = 43.37 N
  6. 6. E = 1.766 × 10⁶ N/C

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