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 15 cm from a point charge of −4 µC. Use k = 8.99 × 10⁹ N·m²/C².

q = −4 µCr = 15 cm

E = N/C

2.Easy

Point charges of +1 µC and +2 µC exert a force of 2 N on each other. How far apart r are they? Give the answer in cm. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +1 µCq₂ = +2 µCF = 2 N

r = cm

3.Medium

A charge of +3 µC and a charge of +6 µC are 60 cm apart. Point P lies on the line between them, 45 cm from the first charge. Find the magnitude of the electric field E at P.

q₁ = +3 µCq₂ = +6 µCr₁ = 45 cmr₂ = 15 cm

E = N/C

4.Medium

A charge of +4 µC and a charge of +4 µC are 20 cm apart. Point P lies on the line between them, 5 cm from the first charge. Find the magnitude of the electric field E at P.

q₁ = +4 µCq₂ = +4 µCr₁ = 5 cmr₂ = 15 cm

E = N/C

5.Hard

Charges of +1 µC and +1 µC are 20 cm apart. Point P lies 10 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 = +1 µCq₂ = +1 µCd = 20 cmh = 10 cm

E = N/C

6.Hard

Charges of +5 µC and −5 µC are 6 cm apart. Point P lies 3 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 = +5 µCq₂ = −5 µCd = 6 cmh = 3 cm

E = N/C

Answer key

1. E = 1.598 × 10⁶ N/C
2. r = 9.482 cm
3. E = 2.264 × 10⁶ N/C
4. E = 1.279 × 10⁷ N/C
5. E = 635689 N/C
6. E = 3.532 × 10⁷ N/C

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