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
−−2 µC−−2 µCr = 2 cm

Two point charges of −2 µC and −2 µC are 2 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

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

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

q1 = −10 µCq2 = +4 µCr = 10 cm
F = N
3.Medium
++6 µC++10 µC++8 µC30 cm + 10 cm

Three point charges lie on a straight line: +6 µC on the left, +8 µC on the right 40 cm away, and +10 µC between them, 30 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 = +6 µCqR = +8 µCqM = +10 µCrL = 30 cmrR = 10 cm
F = N
4.Medium
−−3 µC−−5 µC−−2 µC24 cm + 16 cm

Three point charges lie on a straight line: −3 µC on the left, −2 µC on the right 40 cm away, and −5 µC between them, 24 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 = −3 µCqR = −2 µCqM = −5 µCrL = 24 cmrR = 16 cm
F = N
5.Hard
L = 60 cm10°qq

Two identical small balls, each of mass 2 g, hang from the same point on insulating threads 60 cm long. They are given equal charges and each thread settles at 10° 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 = 60 cmθ = 10°g = 9.81 m/s²
q = nC
6.Hard
+−P2 × 6 cm12 cm+1 µC−1 µC

Charges of +1 µC and −1 µC are 12 cm apart. Point P lies 12 cm from the midpoint between them, on the perpendicular bisector. Find the magnitude of the electric field E at P. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +1 µCq2 = −1 µCd = 12 cmh = 12 cm
E = N/C

Answer key

  1. 1. F = 89.9 N
  2. 2. F = 35.96 N
  3. 3. F = 65.93 N
  4. 4. F = 1.171 N
  5. 5. q = 129.3 nC
  6. 6. E = 446717 N/C

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