1.Easy
Two point charges repel each other with a force of 4 N. The first charge is tripled and the distance between the charges is doubled. Find the new force F′.
F = 4 Nq₁′ = 3·q₁r′ = 2·r
F′ = N
Coulomb’s law & electric fields worksheet with answers
2.Easy
Two point charges of −4 µC and −3 µC are 6 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².
q1 = −4 µCq2 = −3 µCr = 6 cm
F = N
3.Medium
A charge of +10 µC and a charge of −1 µC are 40 cm apart. Point P lies on the line between them, 20 cm from the first charge. Find the magnitude of the electric field E at P.
q1 = +10 µCq2 = −1 µCr1 = 20 cmr2 = 20 cm
E = N/C
4.Medium
A charge of +5 µC and a charge of +2 µC are 30 cm apart. Point P lies on the line between them, 7.5 cm from the first charge. Find the magnitude of the electric field E at P.
q1 = +5 µCq2 = +2 µCr1 = 7.5 cmr2 = 22.5 cm
E = N/C
5.Hard
Three positive point charges sit at the corners of a right triangle: q₃ = 2 µC is at the right-angle corner, q₁ = 1 µC is 3 cm from it along one side and q₂ = 4 µC is 5 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 1 µCq2 = 4 µCq3 = 2 µCr13 = 3 cmr23 = 5 cm
F = N
6.Hard
Three positive point charges sit at the corners of a right triangle: q₃ = 1 µC is at the right-angle corner, q₁ = 6 µC is 5 cm from it along one side and q₂ = 5 µC is 3 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 6 µCq2 = 5 µCq3 = 1 µCr13 = 5 cmr23 = 3 cm
F = N
Answer key
- 1. F′ = 3 N
- 2. F = 29.97 N
- 3. E = 2.472 × 10⁶ N/C
- 4. E = 7.636 × 10⁶ N/C
- 5. F = 35.02 N
- 6. F = 54.41 N
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