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
−−3 µC−−4 µCr = 5 cm

Two point charges of −3 µC and −4 µC are 5 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = −3 µCq2 = −4 µCr = 5 cm
F = N
2.Easy
+ + + + + +− − − − − −e⁻E = 2300 N/C

An electron (charge −1.602 × 10⁻¹⁹ C, mass 9.109 × 10⁻³¹ kg) is in a uniform electric field of 2300 N/C. Ignoring gravity, find the magnitude of its acceleration a.

E = 2300 N/C|q| = 1.602 × 10⁻¹⁹ Cm = 9.109 × 10⁻³¹ kg
a = m/s²
3.Medium
++1 µC++5 µCE = 030 cm

Charges of +1 µC and +5 µC are 30 cm apart. At what distance x from the +1 µC charge, on the line between them, is the electric field zero?

q1 = +1 µCq2 = +5 µCd = 30 cm
x = cm
4.Medium
++5 µC++3 µCP60 cm

A charge of +5 µC and a charge of +3 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 = +5 µCq2 = +3 µCr1 = 15 cmr2 = 45 cm
E = N/C
5.Hard
6 cm6 cm+q1​ = +8 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 = 8 µC is 6 cm from it along one side and q₂ = 4 µC is 6 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q1 = 8 µCq2 = 4 µCq3 = 6 µCr13 = 6 cmr23 = 6 cm
F = N
6.Hard
+−P2 × 10 cm3 cm+1 µC−1 µC

Charges of +1 µC and −1 µC are 20 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 = +1 µCq2 = −1 µCd = 20 cmh = 3 cm
E = N/C

Answer key

  1. 1. F = 43.15 N
  2. 2. a = 4.045 × 10¹⁴ m/s²
  3. 3. x = 9.271 cm
  4. 4. E = 1.865 × 10⁶ N/C
  5. 5. F = 134 N
  6. 6. E = 1.58 × 10⁶ N/C

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