1.Easy
Find the magnitude of the electric field E at a distance of 2 cm from a point charge of −5 nC. Use k = 8.99 × 10⁹ N·m²/C².
q = −5 nCr = 2 cm
E = N/C
Coulomb’s law & electric fields worksheet with answers
2.Easy
Find the magnitude of the electric field E at a distance of 10 cm from a point charge of −5 nC. Use k = 8.99 × 10⁹ N·m²/C².
q = −5 nCr = 10 cm
E = N/C
3.Medium
A charge of +4 µC and a charge of −6 µC are 20 cm apart. Point P lies on the line between them, 12 cm from the first charge. Find the magnitude of the electric field E at P.
q1 = +4 µCq2 = −6 µCr1 = 12 cmr2 = 8 cm
E = N/C
4.Medium
A charge of +6 µC and a charge of −10 µC are 60 cm apart. Point P lies on the line between them, 24 cm from the first charge. Find the magnitude of the electric field E at P.
q1 = +6 µCq2 = −10 µCr1 = 24 cmr2 = 36 cm
E = N/C
5.Hard
Two identical small balls, each of mass 10 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 = 10 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 = 3 µC is at the right-angle corner, q₁ = 2 µC is 5 cm from it along one side and q₂ = 6 µC is 3 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 2 µCq2 = 6 µCq3 = 3 µCr13 = 5 cmr23 = 3 cm
F = N
Answer key
- 1. E = 112375 N/C
- 2. E = 4495 N/C
- 3. E = 1.093 × 10⁷ N/C
- 4. E = 1.63 × 10⁶ N/C
- 5. q = 506.6 nC
- 6. F = 181.1 N
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