Capacitors

• 1.0 nF


  10^9F nano
• 1.0 PF


  10^12F pico
• 1.0 fF


  10^15F femto
• are capacitance terminals swappable


  mostly no
• polarized capacitor


  not swappable cap

  
• capacitor


  swappable cap

  
• explain the inside of a capacitor

  2 metal films rolled up together w an insulator beween them and later packaged.
• 3 ways to store more charges

  1. increase capacitance w/o changing voltage.

  2. increase voltage allowing more charges to be stored.

  3. do both
• Farad's law


  to get the total # of charges stored(coulumbs) we must combine the total of capacitance and volts. Q=CV
• What is another one of Farad's law?

  if 2 terminals touch, charges will become 0.0V which is the quickest way to remove charges.
• What does Farad's law say about plates?

  you need a voltage difference between 2 plates so an electric field.
• what happens when there is more voltage difference at the electric field?

  electric field gets stronger allowing more charges to be stored
• whats another way to strengthen the elctric field?

  add more surface area.
• overlapping area


  where electric field can reach from 1 plate to the other
• the farther metal plates are from each other


  lower voltage and less capacitance
• the closer metal plates are to each other

  higher voltage and more capacitance
• why does the active gate area have high capacitance (C) ?

  the oxide so thin making the distance small= high cap
• what are most capacitors built by?

  mosfets because it creates most of the capacitance w/out taking too much surface area
• what is sheet Rho's equation?


  ρ=R⋅□​/A
• Capacitors in Parallel


  Cab=C1+C2+C3
• capacitors in series


  1/Cab=1/C1+1/C2+1/C3
• reason why too much overlapping layers can be an issue?

  creates unwelcome parasitic capacitance
• which capacitors or more common?

  in series
• what is kirchoff's coulomb law?

  Qab/Cab =Vab
• what happens to charges (Q) when capacitors are in series?

  the charges are shared so they all have the same charge.
• more capacitors in series means


  less capacitance
• why do we get less capacitance in series: the total capacitance decreases because the voltage drop across each capacitor adds up and the smallest capacitance limits how much charge the whole series can hold.
• RC time constant: in resistor and capacitor circuits, its the time it takes voltage of capacitor/resistors to fully be charged.