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

Two point charges of −8 µC and −8 µC are 5 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = −8 µCq₂ = −8 µCr = 5 cm

F = N

2.Easy

Find the magnitude of the electric field E at a distance of 40 cm from a point charge of −40 nC. Use k = 8.99 × 10⁹ N·m²/C².

q = −40 nCr = 40 cm

E = N/C

3.Medium

A charge of +1 µC and a charge of +10 µC are 30 cm apart. Point P lies on the line between them, 12 cm from the first charge. Find the magnitude of the electric field E at P.

q₁ = +1 µCq₂ = +10 µCr₁ = 12 cmr₂ = 18 cm

E = N/C

4.Medium

Charges of +10 µC and +1 µC are 100 cm apart. At what distance x from the +10 µC charge, on the line between them, is the electric field zero?

q₁ = +10 µCq₂ = +1 µCd = 100 cm

x = cm

5.Hard

Three positive point charges sit at the corners of a right triangle: q₃ = 4 µC is at the right-angle corner, q₁ = 2 µC is 3 cm from it along one side and q₂ = 1 µC is 8 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q₁ = 2 µCq₂ = 1 µCq₃ = 4 µCr₁₃ = 3 cmr₂₃ = 8 cm

F = N

6.Hard

Charges of +6 µC and +6 µC are 8 cm apart. Point P lies 10 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 = +6 µCq₂ = +6 µCd = 8 cmh = 10 cm

E = N/C

Answer key

1. F = 230.1 N
2. E = 2247 N/C
3. E = 2.15 × 10⁶ N/C
4. x = 75.97 cm
5. F = 80.11 N
6. E = 8.635 × 10⁶ N/C

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