Coulomb’s law & electric fields worksheet with answers

Free printable Coulomb’s law & electric fields worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

Find the magnitude of the electric field E at a distance of 30 cm from a point charge of +10 nC. Use k = 8.99 × 10⁹ N·m²/C².

q = +10 nCr = 30 cm

E = N/C

2.Easy

Two point charges repel each other with a force of 60 N. The first charge is doubled and the distance between the charges is made four times as large. Find the new force F′.

F = 60 Nq₁′ = 2·q₁r′ = 4·r

F′ = N

3.Medium

A charge of +6 µC and a charge of −8 µC are 20 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 = +6 µCq₂ = −8 µCr₁ = 10 cmr₂ = 10 cm

E = N/C

4.Medium

A charge of +1 µC and a charge of +2 µC are 20 cm apart. Point P lies on the line between them, 8 cm from the first charge. Find the magnitude of the electric field E at P.

q₁ = +1 µCq₂ = +2 µCr₁ = 8 cmr₂ = 12 cm

E = N/C

5.Hard

Charges of +2 µC and −2 µC are 12 cm apart. Point P lies 4 cm from the midpoint between them, on the perpendicular bisector. Find the magnitude of the electric field E at P. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +2 µCq₂ = −2 µCd = 12 cmh = 4 cm

E = N/C

6.Hard

Charges of +4 µC and −4 µC are 10 cm apart. Point P lies 5 cm from the midpoint between them, on the perpendicular bisector. Find the magnitude of the electric field E at P. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +4 µCq₂ = −4 µCd = 10 cmh = 5 cm

E = N/C

Answer key

1. E = 998.9 N/C
2. F′ = 7.5 N
3. E = 1.259 × 10⁷ N/C
4. E = 156076 N/C
5. E = 5.754 × 10⁶ N/C
6. E = 1.017 × 10⁷ N/C

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