Daily Life Examples

  • Hair sticking to a comb
  • Clothes clinging together in the dryer
  • Balloons sticking to a wall after being rubbed on hair
  • Electric shocks when touching a metal doorknob
  • Static cling in clothes, causing them to attract each other
  • Crackling sounds when removing clothes from the dryer
  • Dust particles sticking to a TV or computer screen
  • Shocks from touching someone or something after walking on a carpet
  • Sparks when pulling apart synthetic fabrics
  • Static buildup on plastic wrap, making it cling to itself.

Solved Problem

Two point charges, q1=3 μC and q2=−5 μC, are placed 8 cm apart in a vacuum. Calculate the electrostatic force between them. Coulomb's constant (k) is 8.99×109 N⋅m2/C.

Using Coulomb's Law: F=k⋅(q1⋅q2)/r2

F=(8.99×109)⋅{(3×10−6)⋅(−5×10−6)}/(0.08)2

F≈−22.34 N

Further Reading