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
+ + + + + +− − − − − −e⁻E = 2100 N/C

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
2.Easy
++6 µC−−6 µCr = 4 cm

Two point charges of +6 µC and −6 µC are 4 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q1 = +6 µCq2 = −6 µCr = 4 cm
F = N
3.Medium
−−1 µC++3 µCr = 25 cm

Two identical small metal spheres carry charges of −1 µC and +3 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 = −1 µCq2 = +3 µCr = 25 cm
F = N
4.Medium
++5 µC−−5 µCP50 cm

A charge of +5 µC and a charge of −5 µC are 50 cm apart. Point P lies on the line between them, 37.5 cm from the first charge. Find the magnitude of the electric field E at P.

q1 = +5 µCq2 = −5 µCr1 = 37.5 cmr2 = 12.5 cm
E = N/C
5.Hard
+−P2 × 8 cm8 cm+5 µC−5 µC

Charges of +5 µC and −5 µC are 16 cm apart. Point P lies 8 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 = 16 cmh = 8 cm
E = N/C
6.Hard
++P2 × 4 cm6 cm+6 µC+6 µC

Charges of +6 µC and +6 µC are 8 cm apart. Point P lies 6 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 = +6 µCq2 = +6 µCd = 8 cmh = 6 cm
E = N/C

Answer key

  1. 1. a = 2.011 × 10¹¹ m/s²
  2. 2. F = 202.3 N
  3. 3. F = 0.1438 N
  4. 4. E = 3.196 × 10⁶ N/C
  5. 5. E = 4.966 × 10⁶ N/C
  6. 6. E = 1.726 × 10⁷ N/C

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