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
−−5 µC−−6 µCr = 3 cm

Two point charges of −5 µC and −6 µC are 3 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = −5 µCq2 = −6 µCr = 3 cm
F = N
2.Easy
+ + + + + +− − − − − −e⁻E = 4500 N/C

An electron (charge −1.602 × 10⁻¹⁹ C, mass 9.109 × 10⁻³¹ kg) is in a uniform electric field of 4500 N/C. Ignoring gravity, find the magnitude of its acceleration a.

E = 4500 N/C|q| = 1.602 × 10⁻¹⁹ Cm = 9.109 × 10⁻³¹ kg
a = m/s²
3.Medium
++3 µC−−10 µCP60 cm

A charge of +3 µC and a charge of −10 µC are 60 cm apart. Point P lies on the line between them, 15 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +3 µCq2 = −10 µCr1 = 15 cmr2 = 45 cm
E = N/C
4.Medium
++6 µC−−10 µCP40 cm

A charge of +6 µC and a charge of −10 µC are 40 cm apart. Point P lies on the line between them, 16 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +6 µCq2 = −10 µCr1 = 16 cmr2 = 24 cm
E = N/C
5.Hard
10 cm3 cm+q1​ = +10 µC+q3​ = +6 µC+q2​ = +4 µC

Three positive point charges sit at the corners of a right triangle: q₃ = 6 µC is at the right-angle corner, q₁ = 10 µC is 10 cm from it along one side and q₂ = 4 µC is 3 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 10 µCq2 = 4 µCq3 = 6 µCr13 = 10 cmr23 = 3 cm
F = N
6.Hard
+−P2 × 6 cm12 cm+10 µC−10 µC

Charges of +10 µC and −10 µC are 12 cm apart. Point P lies 12 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 = +10 µCq2 = −10 µCd = 12 cmh = 12 cm
E = N/C

Answer key

  1. 1. F = 299.7 N
  2. 2. a = 7.914 × 10¹⁴ m/s²
  3. 3. E = 1.643 × 10⁶ N/C
  4. 4. E = 3.668 × 10⁶ N/C
  5. 5. F = 245.7 N
  6. 6. E = 4.467 × 10⁶ N/C

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