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 −1 µC are 12 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 = 12 cm

F = N

2.Easy

Two point charges of +4 µC and −5 µC are 15 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +4 µCq₂ = −5 µCr = 15 cm

F = N

3.Medium

Charges of +1 µC and +8 µC are 60 cm apart. At what distance x from the +1 µC charge, on the line between them, is the electric field zero?

q₁ = +1 µCq₂ = +8 µCd = 60 cm

x = cm

4.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

5.Hard

Three positive point charges sit at the corners of a right triangle: q₃ = 6 µC is at the right-angle corner, q₁ = 8 µC is 8 cm from it along one side and q₂ = 1 µC is 5 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q₁ = 8 µCq₂ = 1 µCq₃ = 6 µCr₁₃ = 8 cmr₂₃ = 5 cm

F = N

6.Hard

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

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

F = N

Answer key

1. F = 2.497 N
2. F = 7.991 N
3. x = 15.67 cm
4. x = 12.01 cm
5. F = 70.79 N
6. F = 93.39 N

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