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
++8 µC++6 µCr = 4 cm

Two point charges of +8 µC and +6 µC are 4 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +8 µCq2 = +6 µCr = 4 cm
F = N
2.Easy
−−6 µC−−1 µCr = 12 cm

Two point charges of −6 µC and −1 µC are 12 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = −6 µCq2 = −1 µCr = 12 cm
F = N
3.Medium
++4 µC++2 µCE = 010 cm

Charges of +4 µC and +2 µC are 10 cm apart. At what distance x from the +4 µC charge, on the line between them, is the electric field zero?

q1 = +4 µCq2 = +2 µCd = 10 cm
x = cm
4.Medium
++3 µC++8 µCP10 cm

A charge of +3 µC and a charge of +8 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 = +3 µCq2 = +8 µCr1 = 6 cmr2 = 4 cm
E = N/C
5.Hard
10 cm5 cm+q1​ = +1 µC+q3​ = +10 µC+q2​ = +2 µC

Three positive point charges sit at the corners of a right triangle: q₃ = 10 µC is at the right-angle corner, q₁ = 1 µC is 10 cm from it along one side and q₂ = 2 µC is 5 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 1 µCq2 = 2 µCq3 = 10 µCr13 = 10 cmr23 = 5 cm
F = N
6.Hard
L = 40 cm5°qq

Two identical small balls, each of mass 2 g, hang from the same point on insulating threads 40 cm long. They are given equal charges and each thread settles at 5° from the vertical. Use g = 9.81 m/s². Find the charge q on each ball in nC. Use k = 8.99 × 10⁹ N·m²/C².

m = 2 gL = 40 cmθ = 5°g = 9.81 m/s²
q = nC

Answer key

  1. 1. F = 269.7 N
  2. 2. F = 3.746 N
  3. 3. x = 5.858 cm
  4. 4. E = 3.746 × 10⁷ N/C
  5. 5. F = 72.48 N
  6. 6. q = 30.47 nC

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