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 +4 µC and +3 µC are 3 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +4 µCq₂ = +3 µCr = 3 cm

F = N

2.Easy

Two point charges of −2 µC and −6 µC are 6 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = −2 µCq₂ = −6 µCr = 6 cm

F = N

3.Medium

Charges of +10 µC and +5 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 = +5 µCd = 10 cm

x = cm

4.Medium

A charge of +3 µC and a charge of +10 µC are 20 cm apart. Point P lies on the line between them, 15 cm from the first charge. Find the magnitude of the electric field E at P.

q₁ = +3 µCq₂ = +10 µCr₁ = 15 cmr₂ = 5 cm

E = N/C

5.Hard

Three positive point charges sit at the corners of a right triangle: q₃ = 10 µC is at the right-angle corner, q₁ = 8 µC is 6 cm from it along one side and q₂ = 6 µC is 3 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q₁ = 8 µCq₂ = 6 µCq₃ = 10 µCr₁₃ = 6 cmr₂₃ = 3 cm

F = N

6.Hard

Charges of +5 µC and +5 µC are 6 cm apart. Point P lies 6 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 = +5 µCq₂ = +5 µCd = 6 cmh = 6 cm

E = N/C

Answer key

1. F = 119.9 N
2. F = 29.97 N
3. x = 5.858 cm
4. E = 3.476 × 10⁷ N/C
5. F = 631.8 N
6. E = 1.787 × 10⁷ N/C

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