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
−−3 µC++3 µCr = 12 cm

Two point charges of −3 µC and +3 µC are 12 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = −3 µCq2 = +3 µCr = 12 cm
F = N
2.Easy
++10 µCPr = 3 cm

Find the magnitude of the electric field E at a distance of 3 cm from a point charge of +10 µC. Use k = 8.99 × 10⁹ N·m²/C².

q = +10 µCr = 3 cm
E = N/C
3.Medium
++4 µC−−3 µCP20 cm

A charge of +4 µC and a charge of −3 µC are 20 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 = +4 µCq2 = −3 µCr1 = 15 cmr2 = 5 cm
E = N/C
4.Medium
++2 µC++10 µCP10 cm

A charge of +2 µC and a charge of +10 µC are 10 cm apart. Point P lies on the line between them, 6 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +2 µCq2 = +10 µCr1 = 6 cmr2 = 4 cm
E = N/C
5.Hard
8 cm6 cm+q1​ = +6 µC+q3​ = +1 µC+q2​ = +1 µC

Three positive point charges sit at the corners of a right triangle: q₃ = 1 µC is at the right-angle corner, q₁ = 6 µC is 8 cm from it along one side and q₂ = 1 µC is 6 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 6 µCq2 = 1 µCq3 = 1 µCr13 = 8 cmr23 = 6 cm
F = N
6.Hard
6 cm4 cm+q1​ = +5 µC+q3​ = +1 µC+q2​ = +3 µC

Three positive point charges sit at the corners of a right triangle: q₃ = 1 µC is at the right-angle corner, q₁ = 5 µC is 6 cm from it along one side and q₂ = 3 µC is 4 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 5 µCq2 = 3 µCq3 = 1 µCr13 = 6 cmr23 = 4 cm
F = N

Answer key

  1. 1. F = 5.619 N
  2. 2. E = 9.989 × 10⁷ N/C
  3. 3. E = 1.239 × 10⁷ N/C
  4. 4. E = 5.119 × 10⁷ N/C
  5. 5. F = 8.79 N
  6. 6. F = 20.98 N

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