Capacitors

• Capacitance is the amount of charge stored per unit potential difference
• One farad is defined as the amount of charge stored for one volt of potential difference
• When charging a capacitor, electrons flow from the negative terminal of the cell to the negative plate of the capacitor. An excess of electrons gathers at the negative plate, which repel electrons on the positive plate, causing the plates to have equal but opposite charge.
• When charging a capacitor, half of the energy is always lost due to resistance
• When charging a capacitor, the current-time graph is given via:

  
• When charging a capacitor, the voltage-time graph is given via:

  
• When charging/discharging capacitors, we include resistors to reduce the current.
• The voltage/current - time graphs for the discharge of a capacitor are the same: they are both an exponential decay.