Chapter 21- Capacitance

• Capacitors are electrical components which store charge
• A capacitor is made up of two metal plates separated by a dielectric
• The longer side of a cell is positively charged
• When a capacitor is connected to a cell Electrons are removed from the plate on the positive side of the cell which becomes deficient in electrons and acquired a positive charge. At the same time electrons are deposited into the other plate causing it to acquire a negative charge.
• Capacitance is defined as the charge stored per unit pd across it
• The capacitance of capacitors connected in parallel is equal to the sum of their individual capacitances
• The capacitance for capacitors connected in series is equal to the reciprocal of the sum of the reciprocals of the individual capacitances
• Work is done to add and remove electrons from the capacitors plates, therefore the energy stored in a capacitor is supplied by the energy of a battery or a power supply
• The area under a pd charge graph is equal to the work done
• The discharging curves for voltage, current and charge are all the same

  
• Capacitors can be used for smoothing ac current to produce a smooth dc output

  
• Capacitors can be used for flashed to release a high Power burst in a short amount of time