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
−−2 µC−−4 µCr = 20 cm

Two point charges of −2 µC and −4 µC are 20 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = −2 µCq2 = −4 µCr = 20 cm
F = N
2.Easy
++5 µC++4 µCr = 25 cm

Two point charges of +5 µC and +4 µC are 25 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +5 µCq2 = +4 µCr = 25 cm
F = N
3.Medium
++5 µC−−3 µCr = 10 cm

Two identical small metal spheres carry charges of +5 µC and −3 µC. They are touched together and then put back 10 cm apart. Find the magnitude of the force F between them now. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +5 µCq2 = −3 µCr = 10 cm
F = N
4.Medium
++6 µC−−6 µCP10 cm

A charge of +6 µC and a charge of −6 µC are 10 cm apart. Point P lies on the line between them, 7.5 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +6 µCq2 = −6 µCr1 = 7.5 cmr2 = 2.5 cm
E = N/C
5.Hard
8 cm6 cm+q1​ = +2 µC+q3​ = +6 µC+q2​ = +6 µC

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

q1 = 2 µCq2 = 6 µCq3 = 6 µCr13 = 8 cmr23 = 6 cm
F = N
6.Hard
++P2 × 10 cm5 cm+8 µC+8 µC

Charges of +8 µC and +8 µC are 20 cm apart. Point P lies 5 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 = +8 µCq2 = +8 µCd = 20 cmh = 5 cm
E = N/C

Answer key

  1. 1. F = 1.798 N
  2. 2. F = 2.877 N
  3. 3. F = 0.899 N
  4. 4. E = 9.589 × 10⁷ N/C
  5. 5. F = 91.47 N
  6. 6. E = 5.146 × 10⁶ N/C

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