Diket:

Muatan q1 = 20 µC

Muatan q2 = 30 µC

Jarak antara muatan r = 20 cm = 0.2 m

Permitivitas vakum ε0 = 8.854 × 10⁻¹² C²/Nm²

Permitivitas relatif suatu bahan εr = 3p

a.

F = k x (q1 x q2) / r²

= 9 × 10⁹ Nm²/C² x (20 × 10⁻⁶ C) x (30 × 10⁻⁶ C) / (0.2 m)²

= 2.7 × 10⁻³ N

besar gaya pada muatan :

Fq1 = Fq2 = 1.35 × 10⁻³ N (arahnya berlawanan)

b. ε = εr x ε0 = 3 x 8.854 × 10⁻¹² C²/Nm² = 26.562 × 10⁻¹² C²/Nm²

gaya listrik kedua muatan

F = k x (q1 x q2) / (ε x r)²

= 9 × 10⁹ Nm²/C² x (20 × 10⁻⁶ C) x (30 × 10⁻⁶ C) / [(26.562 × 10⁻¹² C²/Nm²) x (0.2 m)²]

= 1.8 × 10⁻³ N

besar gaya pada muatan

Fq1 = Fq2 = 0.9 × 10⁻³ N (arahnya berlawanan)