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 +10 µC are 8 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = −8 µCq₂ = +10 µCr = 8 cm

F = N

2.Easy

Two point charges of +3 µC and −10 µC are 15 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +3 µCq₂ = −10 µCr = 15 cm

F = N

3.Medium

Charges of +6 µC and +10 µC are 30 cm apart. At what distance x from the +6 µC charge, on the line between them, is the electric field zero?

q₁ = +6 µCq₂ = +10 µCd = 30 cm

x = cm

4.Medium

Charges of +1 µC and +5 µC are 30 cm apart. At what distance x from the +1 µC charge, on the line between them, is the electric field zero?

q₁ = +1 µCq₂ = +5 µCd = 30 cm

x = cm

5.Hard

Three positive point charges sit at the corners of a right triangle: q₃ = 8 µC is at the right-angle corner, q₁ = 3 µC is 10 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 = 3 µCq₂ = 1 µCq₃ = 8 µCr₁₃ = 10 cmr₂₃ = 8 cm

F = N

6.Hard

Three positive point charges sit at the corners of a right triangle: q₃ = 5 µC is at the right-angle corner, q₁ = 5 µC is 3 cm from it along one side and q₂ = 2 µC is 5 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q₁ = 5 µCq₂ = 2 µCq₃ = 5 µCr₁₃ = 3 cmr₂₃ = 5 cm

F = N

Answer key

1. F = 112.4 N
2. F = 11.99 N
3. x = 13.09 cm
4. x = 9.271 cm
5. F = 24.33 N
6. F = 252.3 N

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