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
++6 µC−−10 µCr = 4 cm

Two point charges of +6 µC and −10 µC are 4 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +6 µCq2 = −10 µCr = 4 cm
F = N
2.Easy
++6 µC−−6 µCr = 20 cm

Two point charges of +6 µC and −6 µC are 20 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +6 µCq2 = −6 µCr = 20 cm
F = N
3.Medium
++5 µC−−10 µCP40 cm

A charge of +5 µC and a charge of −10 µC are 40 cm apart. Point P lies on the line between them, 24 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +5 µCq2 = −10 µCr1 = 24 cmr2 = 16 cm
E = N/C
4.Medium
++6 µC++10 µCP30 cm

A charge of +6 µC and a charge of +10 µC are 30 cm apart. Point P lies on the line between them, 22.5 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +6 µCq2 = +10 µCr1 = 22.5 cmr2 = 7.5 cm
E = N/C
5.Hard
6 cm5 cm+q1​ = +2 µC+q3​ = +6 µC+q2​ = +1 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 6 cm from it along one side and q₂ = 1 µC is 5 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 2 µCq2 = 1 µCq3 = 6 µCr13 = 6 cmr23 = 5 cm
F = N
6.Hard
5 cm3 cm+q1​ = +10 µC+q3​ = +3 µC+q2​ = +4 µC

Three positive point charges sit at the corners of a right triangle: q₃ = 3 µC is at the right-angle corner, q₁ = 10 µC is 5 cm from it along one side and q₂ = 4 µC is 3 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 10 µCq2 = 4 µCq3 = 3 µCr13 = 5 cmr23 = 3 cm
F = N

Answer key

  1. 1. F = 337.1 N
  2. 2. F = 8.091 N
  3. 3. E = 4.292 × 10⁶ N/C
  4. 4. E = 1.492 × 10⁷ N/C
  5. 5. F = 36.93 N
  6. 6. F = 161.3 N

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