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 +10 µC and +3 µC are 20 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +10 µCq₂ = +3 µCr = 20 cm

F = N

2.Easy

Two point charges of +4 µC and +2 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 = +2 µCr = 3 cm

F = N

3.Medium

Charges of +1 µC and +10 µC are 50 cm apart. At what distance x from the +1 µC charge, on the line between them, is the electric field zero?

q₁ = +1 µCq₂ = +10 µCd = 50 cm

x = cm

4.Medium

A charge of +1 µC and a charge of −2 µC are 50 cm apart. Point P lies on the line between them, 37.5 cm from the first charge. Find the magnitude of the electric field E at P.

q₁ = +1 µCq₂ = −2 µCr₁ = 37.5 cmr₂ = 12.5 cm

E = N/C

5.Hard

Charges of +1 µC and −1 µC are 20 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 = 20 cmh = 4 cm

E = N/C

6.Hard

Three positive point charges sit at the corners of a right triangle: q₃ = 1 µC is at the right-angle corner, q₁ = 1 µC is 6 cm from it along one side and q₂ = 3 µC is 8 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q₁ = 1 µCq₂ = 3 µCq₃ = 1 µCr₁₃ = 6 cmr₂₃ = 8 cm

F = N

Answer key

1. F = 6.742 N
2. F = 79.91 N
3. x = 12.01 cm
4. E = 1.215 × 10⁶ N/C
5. E = 1.439 × 10⁶ N/C
6. F = 4.898 N

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