6.1.1 Capacitors

• A Capacitor consists of two metallic plates separated from each other by an insulator known as a dielectric e.g. air, ceramic, paper
• When the battery is turned on, electrons flow and are deposited on one plate of the capacitor that is connected to the negative terminal of the battery.

  These electrons repel and push electrons on the other plate leaving behind a positive plate that is electron deficient.

  
  

  Both plates aquire a equal and opposite charge

  
  

  Capacitor is now fully charged
• The capacitance of a capacitor is defined as the charge per unit p.d across it

  C = Q/V can also be written as Q=C*V
• For Capacitors in Parallel:

  The total capacitance together is greater than their individual capacitances

  Total Capacitance = The sum of capacitances on capacitors = Ct=C1+C2+C3 etc..

  The total p.d is the same everywhere
• For Capacitors in Series:

  The total capacitance together is less than their individual capacitances

  The charge stored by each capacitor is the same

  The total capacitance is given by:

  1/Ct = 1/C1 + 1/C2 + 1/C3