1.Easy
Two point charges repel each other with a force of 56 N. The first charge is tripled and the distance between the charges is made four times as large. Find the new force F′.
F = 56 Nq₁′ = 3·q₁r′ = 4·r
F′ = N
Coulomb’s law & electric fields worksheet with answers
2.Easy
Two point charges of −4 µC and +4 µC are 20 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².
q1 = −4 µCq2 = +4 µCr = 20 cm
F = N
3.Medium
A charge of +5 µC and a charge of +2 µC are 60 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 = +5 µCq2 = +2 µCr1 = 15 cmr2 = 45 cm
E = N/C
4.Medium
A charge of +10 µC and a charge of +2 µC are 30 cm apart. Point P lies on the line between them, 22.5 cm from the first charge. Find the magnitude of the electric field E at P.
q1 = +10 µCq2 = +2 µCr1 = 22.5 cmr2 = 7.5 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 = 4 µC is 4 cm from it along one side and q₂ = 1 µC is 10 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 4 µCq2 = 1 µCq3 = 10 µCr13 = 4 cmr23 = 10 cm
F = N
6.Hard
Three positive point charges sit at the corners of a right triangle: q₃ = 3 µC is at the right-angle corner, q₁ = 3 µC is 3 cm from it along one side and q₂ = 5 µC is 6 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 3 µCq2 = 5 µCq3 = 3 µCr13 = 3 cmr23 = 6 cm
F = N
Answer key
- 1. F′ = 10.5 N
- 2. F = 3.596 N
- 3. E = 1.909 × 10⁶ N/C
- 4. E = 1.421 × 10⁶ N/C
- 5. F = 224.9 N
- 6. F = 97.39 N
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