Static Electricity

Static Electricity

1. Electric charge (Q)

   • Excess or deficiency of electrons
   • Coulomb (C) 1C
     • 1mC - ! millicoloumb - 1x10`3
       • 1pC - ! micro coulomb - 1x10`6
         • 1nC - 1 nanocoulomb - 1x 10`9
           • 1pc - 1 picocoulomb - 1x10`12
   • Like charges repel each other
   • Unlike charges attract each other
   • Gold leaf electroscope

2. Electrification

   • By contact
     • Polythene
       • Negative
     • Perspex
       • Positive
   • Conductor
     • Any substance through which electric charge can flow
   • Insulator
     • Any substance through which electric charge can't flow
   • By induction

3. Point discharge

   • All static charges reside on the outside of a conductor
     • Accumulates where the conductor is most pointed
   • Ions in the air are either strongly attracted or repelled from the tip of a charged conductor and move towards or away from it
   • Demonstrated using a Van de Graaf generator

4. Coulomb's Law

   • Electrostatic force between two point charges
     • Proportional to the product of their charges
     • Inversely proportional to the square of the distance between the charges

5. Electric fields

   • The region of space in which electric charges at rest experience an electrostatic force
   • Electric field lines
     • Line along which a positive charge would move if placed in the electric field
   • Electric field strength
     • Force per unit positive charge at a point in an electric field
     • Newton per coulomb