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−−1 µCr = 4 cm

Two point charges of −2 µC and −1 µC are 4 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = −2 µCq2 = −1 µCr = 4 cm
F = N
2.Easy
+ + + + + +− − − − − −e⁻E = 800 N/C

A proton (charge 1.602 × 10⁻¹⁹ C, mass 1.673 × 10⁻²⁷ kg) is in a uniform electric field of 800 N/C. Ignoring gravity, find the magnitude of its acceleration a.

E = 800 N/C|q| = 1.602 × 10⁻¹⁹ Cm = 1.673 × 10⁻²⁷ kg
a = m/s²
3.Medium
−−6 µC−−5 µC++6 µC20 cm + 20 cm

Three point charges lie on a straight line: −6 µC on the left, +6 µC on the right 40 cm away, and −5 µC between them, 20 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 = +6 µCqM = −5 µCrL = 20 cmrR = 20 cm
F = N
4.Medium
−−2 µC++10 µC−−4 µC5 cm + 5 cm

Three point charges lie on a straight line: −2 µC on the left, −4 µC on the right 10 cm away, and +10 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 = −2 µCqR = −4 µCqM = +10 µCrL = 5 cmrR = 5 cm
F = N
5.Hard
3 cm4 cm+q1​ = +3 µC+q3​ = +6 µC+q2​ = +4 µC

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

q1 = 3 µCq2 = 4 µCq3 = 6 µCr13 = 3 cmr23 = 4 cm
F = N
6.Hard
++P2 × 8 cm12 cm+4 µC+4 µC

Charges of +4 µC and +4 µC are 16 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 = +4 µCq2 = +4 µCd = 16 cmh = 12 cm
E = N/C

Answer key

  1. 1. F = 11.24 N
  2. 2. a = 7.66 × 10¹⁰ m/s²
  3. 3. F = 13.48 N
  4. 4. F = 71.92 N
  5. 5. F = 224.7 N
  6. 6. E = 2.877 × 10⁶ N/C

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