1.Easy
Two point charges of −1 µC and +8 µC are 10 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².
q1 = −1 µCq2 = +8 µCr = 10 cm
F = N
Coulomb’s law & electric fields worksheet with answers
2.Easy
Two point charges repel each other with a force of 34 N. The first charge is doubled and the distance between the charges is made four times as large. Find the new force F′.
F = 34 Nq₁′ = 2·q₁r′ = 4·r
F′ = N
3.Medium
A charge of +6 µC and a charge of −5 µC are 50 cm apart. Point P lies on the line between them, 12.5 cm from the first charge. Find the magnitude of the electric field E at P.
q1 = +6 µCq2 = −5 µCr1 = 12.5 cmr2 = 37.5 cm
E = N/C
4.Medium
A charge of +10 µC and a charge of −1 µC are 40 cm apart. Point P lies on the line between them, 10 cm from the first charge. Find the magnitude of the electric field E at P.
q1 = +10 µCq2 = −1 µCr1 = 10 cmr2 = 30 cm
E = N/C
5.Hard
Two identical small balls, each of mass 1 g, hang from the same point on insulating threads 80 cm long. They are given equal charges and each thread settles at 12° from the vertical. Use g = 9.81 m/s². Find the charge q on each ball in nC. Use k = 8.99 × 10⁹ N·m²/C².
m = 1 gL = 80 cmθ = 12°g = 9.81 m/s²
q = nC
6.Hard
Three positive point charges sit at the corners of a right triangle: q₃ = 1 µC is at the right-angle corner, q₁ = 5 µC is 4 cm from it along one side and q₂ = 4 µC is 6 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 5 µCq2 = 4 µCq3 = 1 µCr13 = 4 cmr23 = 6 cm
F = N
Answer key
- 1. F = 7.192 N
- 2. F′ = 4.25 N
- 3. E = 3.772 × 10⁶ N/C
- 4. E = 9.09 × 10⁶ N/C
- 5. q = 160.2 nC
- 6. F = 29.82 N
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