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

Find the magnitude of the electric field E at a distance of 2 cm from a point charge of +2 µC. Use k = 8.99 × 10⁹ N·m²/C².

q = +2 µCr = 2 cm

E = N/C

2.Easy

An electron (charge −1.602 × 10⁻¹⁹ C, mass 9.109 × 10⁻³¹ kg) is in a uniform electric field of 1200 N/C. Ignoring gravity, find the magnitude of its acceleration a.

E = 1200 N/C|q| = 1.602 × 10⁻¹⁹ Cm = 9.109 × 10⁻³¹ kg

a = m/s²

3.Medium

Charges of +10 µC and +2 µC are 10 cm apart. At what distance x from the +10 µC charge, on the line between them, is the electric field zero?

q₁ = +10 µCq₂ = +2 µCd = 10 cm

x = cm

4.Medium

Charges of +8 µC and +4 µC are 10 cm apart. At what distance x from the +8 µC charge, on the line between them, is the electric field zero?

q₁ = +8 µCq₂ = +4 µCd = 10 cm

x = cm

5.Hard

Charges of +1 µC and +1 µC are 8 cm apart. Point P lies 4 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 = 8 cmh = 4 cm

E = N/C

6.Hard

Three positive point charges sit at the corners of a right triangle: q₃ = 5 µC is at the right-angle corner, q₁ = 8 µC is 8 cm from it along one side and q₂ = 1 µC is 10 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q₁ = 8 µCq₂ = 1 µCq₃ = 5 µCr₁₃ = 8 cmr₂₃ = 10 cm

F = N

Answer key

1. E = 4.495 × 10⁷ N/C
2. a = 2.11 × 10¹⁴ m/s²
3. x = 6.91 cm
4. x = 5.858 cm
5. E = 3.973 × 10⁶ N/C
6. F = 56.37 N

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