1.Easy
Two point charges repel each other with a force of 8 N. The first charge is doubled and the distance between the charges is tripled. Find the new force F′.
F = 8 Nq₁′ = 2·q₁r′ = 3·r
F′ = N
Coulomb’s law & electric fields worksheet with answers
2.Easy
Two point charges of −10 µC and +10 µC are 3 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².
q1 = −10 µCq2 = +10 µCr = 3 cm
F = N
3.Medium
A charge of +5 µC and a charge of +1 µC are 60 cm apart. Point P lies on the line between them, 36 cm from the first charge. Find the magnitude of the electric field E at P.
q1 = +5 µCq2 = +1 µCr1 = 36 cmr2 = 24 cm
E = N/C
4.Medium
A charge of +1 µC and a charge of −5 µC are 10 cm apart. Point P lies on the line between them, 6 cm from the first charge. Find the magnitude of the electric field E at P.
q1 = +1 µCq2 = −5 µCr1 = 6 cmr2 = 4 cm
E = N/C
5.Hard
Two identical small balls, each of mass 1 g, hang from the same point on insulating threads 50 cm long. They are given equal charges and each thread settles at 8° 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 = 50 cmθ = 8°g = 9.81 m/s²
q = nC
6.Hard
Three positive point charges sit at the corners of a right triangle: q₃ = 10 µC is at the right-angle corner, q₁ = 5 µC is 8 cm from it along one side and q₂ = 3 µC is 8 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 5 µCq2 = 3 µCq3 = 10 µCr13 = 8 cmr23 = 8 cm
F = N
Answer key
- 1. F′ = 1.778 N
- 2. F = 998.9 N
- 3. E = 190760 N/C
- 4. E = 3.059 × 10⁷ N/C
- 5. q = 54.5 nC
- 6. F = 81.91 N
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