1.Easy
Two point charges repel each other with a force of 30 N. The first charge is halved and the distance between the charges is made four times as large. Find the new force F′.
F = 30 Nq₁′ = 0.5·q₁r′ = 4·r
F′ = N
Coulomb’s law & electric fields worksheet with answers
2.Easy
A proton (charge 1.602 × 10⁻¹⁹ C, mass 1.673 × 10⁻²⁷ kg) is in a uniform electric field of 2100 N/C. Ignoring gravity, find the magnitude of its acceleration a.
E = 2100 N/C|q| = 1.602 × 10⁻¹⁹ Cm = 1.673 × 10⁻²⁷ kg
a = m/s²
3.Medium
A charge of +5 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 = +5 µCq2 = +1 µCr1 = 10 cmr2 = 30 cm
E = N/C
4.Medium
Two identical small metal spheres carry charges of +6 µC and +5 µC. They are touched together and then put back 25 cm apart. Find the magnitude of the force F between them now. Use k = 8.99 × 10⁹ N·m²/C².
q1 = +6 µCq2 = +5 µCr = 25 cm
F = N
5.Hard
Three positive point charges sit at the corners of a right triangle: q₃ = 2 µC is at the right-angle corner, q₁ = 2 µC is 6 cm from it along one side and q₂ = 8 µC is 5 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 2 µCq2 = 8 µCq3 = 2 µCr13 = 6 cmr23 = 5 cm
F = N
6.Hard
Three positive point charges sit at the corners of a right triangle: q₃ = 3 µC is at the right-angle corner, q₁ = 3 µC is 6 cm from it along one side and q₂ = 1 µC is 4 cm from it along the other side. Find the magnitude of the net electric force F on q₃.
q1 = 3 µCq2 = 1 µCq3 = 3 µCr13 = 6 cmr23 = 4 cm
F = N
Answer key
- 1. F′ = 0.9375 N
- 2. a = 2.011 × 10¹¹ m/s²
- 3. E = 4.395 × 10⁶ N/C
- 4. F = 4.351 N
- 5. F = 58.4 N
- 6. F = 28.09 N
Full step-by-step solutions: practise this topic on examproblems.com.