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
−−6 µC++4 µCr = 8 cm

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

q1 = −6 µCq2 = +4 µCr = 8 cm
F = N
2.Easy
++10 µC++10 µCr = 12 cm

Two point charges of +10 µC and +10 µC are 12 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +10 µCq2 = +10 µCr = 12 cm
F = N
3.Medium
++10 µC++2 µCr = 5 cm

Two identical small metal spheres carry charges of +10 µC and +2 µC. They are touched together and then put back 5 cm apart. Find the magnitude of the force F between them now. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +10 µCq2 = +2 µCr = 5 cm
F = N
4.Medium
++10 µC−−3 µCP10 cm

A charge of +10 µC and a charge of −3 µC are 10 cm apart. Point P lies on the line between them, 7.5 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +10 µCq2 = −3 µCr1 = 7.5 cmr2 = 2.5 cm
E = N/C
5.Hard
6 cm4 cm+q1​ = +3 µC+q3​ = +1 µC+q2​ = +10 µC

Three positive point charges sit at the corners of a right triangle: q₃ = 1 µC is at the right-angle corner, q₁ = 3 µC is 6 cm from it along one side and q₂ = 10 µC is 4 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 3 µCq2 = 10 µCq3 = 1 µCr13 = 6 cmr23 = 4 cm
F = N
6.Hard
+ + + + + +− − − − − −e⁻3.5 × 10⁷ m/s6 cmE = 3600 N/C

An electron enters the uniform field between two parallel plates moving parallel to them at 3.5 × 10⁷ m/s. The plates are 6 cm long and the field between them is 3600 N/C. Electron charge 1.602 × 10⁻¹⁹ C, mass 9.109 × 10⁻³¹ kg; ignore gravity. How far y is it deflected sideways when it leaves the plates? Give the answer in mm.

v₀ = 3.5 × 10⁷ m/sL = 6 cmE = 3600 N/Ce = 1.602 × 10⁻¹⁹ Cme = 9.109 × 10⁻³¹ kg
y = mm

Answer key

  1. 1. F = 33.71 N
  2. 2. F = 62.43 N
  3. 3. F = 129.5 N
  4. 4. E = 5.913 × 10⁷ N/C
  5. 5. F = 56.68 N
  6. 6. y = 0.9303 mm

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