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 8 cm from a point charge of −10 nC. Use k = 8.99 × 10⁹ N·m²/C².

q = −10 nCr = 8 cm

E = N/C

2.Easy

Two point charges of −4 µC and +1 µC are 30 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = −4 µCq₂ = +1 µCr = 30 cm

F = N

3.Medium

A charge of +10 µC and a charge of −1 µC are 10 cm apart. Point P lies on the line between them, 2.5 cm from the first charge. Find the magnitude of the electric field E at P.

q₁ = +10 µCq₂ = −1 µCr₁ = 2.5 cmr₂ = 7.5 cm

E = N/C

4.Medium

Charges of +1 µC and +2 µC are 10 cm apart. At what distance x from the +1 µC charge, on the line between them, is the electric field zero?

q₁ = +1 µCq₂ = +2 µCd = 10 cm

x = cm

5.Hard

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

E = N/C

6.Hard

Three positive point charges sit at the corners of a right triangle: q₃ = 8 µC is at the right-angle corner, q₁ = 5 µC is 4 cm from it along one side and q₂ = 8 µC is 6 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q₁ = 5 µCq₂ = 8 µCq₃ = 8 µCr₁₃ = 4 cmr₂₃ = 6 cm

F = N

Answer key

1. E = 14047 N/C
2. F = 0.3996 N
3. E = 1.454 × 10⁸ N/C
4. x = 4.142 cm
5. E = 1.005 × 10⁶ N/C
6. F = 275.8 N

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