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
−−5 µC−−8 µCr = 10 cm

Two point charges of −5 µC and −8 µC are 10 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

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

Find the magnitude of the electric field E at a distance of 8 cm from a point charge of +10 nC. Use k = 8.99 × 10⁹ N·m²/C².

q = +10 nCr = 8 cm
E = N/C
3.Medium
++2 µC−−2 µCP60 cm

A charge of +2 µC and a charge of −2 µC are 60 cm apart. Point P lies on the line between them, 15 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +2 µCq2 = −2 µCr1 = 15 cmr2 = 45 cm
E = N/C
4.Medium
−−1 µC−−4 µC−−3 µC5 cm + 5 cm

Three point charges lie on a straight line: −1 µC on the left, −3 µC on the right 10 cm away, and −4 µC between them, 5 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 = −3 µCqM = −4 µCrL = 5 cmrR = 5 cm
F = N
5.Hard
4 cm10 cm+q1​ = +10 µC+q3​ = +10 µC+q2​ = +4 µC

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

q1 = 10 µCq2 = 4 µCq3 = 10 µCr13 = 4 cmr23 = 10 cm
F = N
6.Hard
5 cm4 cm+q1​ = +5 µC+q3​ = +5 µC+q2​ = +8 µC

Three positive point charges sit at the corners of a right triangle: q₃ = 5 µC is at the right-angle corner, q₁ = 5 µC is 5 cm from it along one side and q₂ = 8 µC is 4 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 5 µCq2 = 8 µCq3 = 5 µCr13 = 5 cmr23 = 4 cm
F = N

Answer key

  1. 1. F = 35.96 N
  2. 2. E = 14047 N/C
  3. 3. E = 887901 N/C
  4. 4. F = 28.77 N
  5. 5. F = 563 N
  6. 6. F = 242.1 N

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