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.

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1.Easy
++8 µC−−3 µCr = 30 cm

Two point charges of +8 µC and −3 µC are 30 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +8 µCq2 = −3 µCr = 30 cm
F = N
2.Easy
++6 µCPr = 8 cm

Find the magnitude of the electric field E at a distance of 8 cm from a point charge of +6 µC. Use k = 8.99 × 10⁹ N·m²/C².

q = +6 µCr = 8 cm
E = N/C
3.Medium
++5 µC++6 µCP60 cm

A charge of +5 µC and a charge of +6 µC are 60 cm apart. Point P lies on the line between them, 45 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +5 µCq2 = +6 µCr1 = 45 cmr2 = 15 cm
E = N/C
4.Medium
++6 µC++3 µCE = 080 cm

Charges of +6 µC and +3 µC are 80 cm apart. At what distance x from the +6 µC charge, on the line between them, is the electric field zero?

q1 = +6 µCq2 = +3 µCd = 80 cm
x = cm
5.Hard
+ + + + + +− − − − − −e⁻4 × 10⁷ m/s6 cmE = 3300 N/C

An electron enters the uniform field between two parallel plates moving parallel to them at 4 × 10⁷ m/s. The plates are 6 cm long and the field between them is 3300 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 = 6 cmE = 3300 N/Ce = 1.602 × 10⁻¹⁹ Cme = 9.109 × 10⁻³¹ kg
y = mm
6.Hard
+ + + + + +− − − − − −e⁻1 × 10⁷ m/s4 cmE = 1300 N/C

An electron enters the uniform field between two parallel plates moving parallel to them at 1 × 10⁷ m/s. The plates are 4 cm long and the field between them is 1300 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 × 10⁷ m/sL = 4 cmE = 1300 N/Ce = 1.602 × 10⁻¹⁹ Cme = 9.109 × 10⁻³¹ kg
y = mm

Answer key

  1. 1. F = 2.397 N
  2. 2. E = 8.428 × 10⁶ N/C
  3. 3. E = 2.175 × 10⁶ N/C
  4. 4. x = 46.86 cm
  5. 5. y = 0.6529 mm
  6. 6. y = 1.829 mm

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