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.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
−−1 µCPr = 2 cm

Find the magnitude of the electric field E at a distance of 2 cm from a point charge of −1 µC. Use k = 8.99 × 10⁹ N·m²/C².

q = −1 µCr = 2 cm
E = N/C
2.Easy
++5 µC++3 µCr = ?

Point charges of +5 µC and +3 µC exert a force of 1 N on each other. How far apart r are they? Give the answer in cm. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +5 µCq2 = +3 µCF = 1 N
r = cm
3.Medium
++3 µC++4 µCP40 cm

A charge of +3 µC and a charge of +4 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 = +3 µCq2 = +4 µCr1 = 24 cmr2 = 16 cm
E = N/C
4.Medium
++1 µC−−3 µC−−2 µC15 cm + 5 cm

Three point charges lie on a straight line: +1 µC on the left, −2 µC on the right 20 cm away, and −3 µC between them, 15 cm from the left charge. Find the magnitude of the net electric force F on the middle charge. Use k = 8.99 × 10⁹ N·m²/C².

qL = +1 µCqR = −2 µCqM = −3 µCrL = 15 cmrR = 5 cm
F = N
5.Hard
5 cm6 cm+q1​ = +2 µC+q3​ = +10 µC+q2​ = +5 µC

Three positive point charges sit at the corners of a right triangle: q₃ = 10 µC is at the right-angle corner, q₁ = 2 µC is 5 cm from it along one side and q₂ = 5 µC is 6 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 2 µCq2 = 5 µCq3 = 10 µCr13 = 5 cmr23 = 6 cm
F = N
6.Hard
10 cm4 cm+q1​ = +6 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 = 6 µC is 10 cm from it along one side and q₂ = 6 µC is 4 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 6 µCq2 = 6 µCq3 = 6 µCr13 = 10 cmr23 = 4 cm
F = N

Answer key

  1. 1. E = 2.248 × 10⁷ N/C
  2. 2. r = 36.72 cm
  3. 3. E = 936458 N/C
  4. 4. F = 22.77 N
  5. 5. F = 144.1 N
  6. 6. F = 204.8 N

Full step-by-step solutions: practise this topic on examproblems.com.