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
++10 µC++4 µCr = 30 cm

Two point charges of +10 µC and +4 µC are 30 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 = 30 cm
F = N
2.Easy
++6 µC++6 µCr = 12 cm

Two point charges of +6 µC and +6 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 = +6 µCr = 12 cm
F = N
3.Medium
++1 µC++5 µCr = 20 cm

Two identical small metal spheres carry charges of +1 µC and +5 µC. They are touched together and then put back 20 cm apart. Find the magnitude of the force F between them now. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +1 µCq2 = +5 µCr = 20 cm
F = N
4.Medium
++3 µC++6 µCP50 cm

A charge of +3 µC and a charge of +6 µC are 50 cm apart. Point P lies on the line between them, 37.5 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +3 µCq2 = +6 µCr1 = 37.5 cmr2 = 12.5 cm
E = N/C
5.Hard
+ + + + + +− − − − − −e⁻1.5 × 10⁷ m/s3 cmE = 4900 N/C

An electron enters the uniform field between two parallel plates moving parallel to them at 1.5 × 10⁷ m/s. The plates are 3 cm long and the field between them is 4900 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 = 1.5 × 10⁷ m/sL = 3 cmE = 4900 N/Ce = 1.602 × 10⁻¹⁹ Cme = 9.109 × 10⁻³¹ kg
y = mm
6.Hard
+ + + + + +− − − − − −e⁻4 × 10⁷ m/s4 cmE = 4700 N/C

An electron enters the uniform field between two parallel plates moving parallel to them at 4 × 10⁷ m/s. The plates are 4 cm long and the field between them is 4700 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 = 4 × 10⁷ m/sL = 4 cmE = 4700 N/Ce = 1.602 × 10⁻¹⁹ Cme = 9.109 × 10⁻³¹ kg
y = mm

Answer key

  1. 1. F = 3.996 N
  2. 2. F = 22.47 N
  3. 3. F = 2.023 N
  4. 4. E = 3.26 × 10⁶ N/C
  5. 5. y = 1.724 mm
  6. 6. y = 0.4133 mm

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