1.Easy
Two point charges of +4 µC and −5 µC are 3 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².
q1 = +4 µCq2 = −5 µCr = 3 cm
F = N
Coulomb’s law & electric fields worksheet with answers
2.Easy
An electron (charge −1.602 × 10⁻¹⁹ C, mass 9.109 × 10⁻³¹ kg) is in a uniform electric field of 2400 N/C. Ignoring gravity, find the magnitude of its acceleration a.
E = 2400 N/C|q| = 1.602 × 10⁻¹⁹ Cm = 9.109 × 10⁻³¹ kg
a = m/s²
3.Medium
Three point charges lie on a straight line: +5 µC on the left, +8 µC on the right 30 cm away, and +1 µC between them, 22.5 cm from the left charge. Find the magnitude of the net electric force F on the middle charge. Use k = 8.99 × 10⁹ N·m²/C².
qL = +5 µCqR = +8 µCqM = +1 µCrL = 22.5 cmrR = 7.5 cm
F = N
4.Medium
A charge of +3 µC and a charge of −5 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 = +3 µCq2 = −5 µCr1 = 20 cmr2 = 20 cm
E = N/C
5.Hard
Two identical small balls, each of mass 3 g, hang from the same point on insulating threads 60 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 = 3 gL = 60 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 = 3 µC is 6 cm from it along one side and q₂ = 5 µC is 5 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 3 µCq2 = 5 µCq3 = 10 µCr13 = 6 cmr23 = 5 cm
F = N
Answer key
- 1. F = 199.8 N
- 2. a = 4.221 × 10¹⁴ m/s²
- 3. F = 11.9 N
- 4. E = 1.798 × 10⁶ N/C
- 5. q = 113.3 nC
- 6. F = 194.8 N
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