physics p1 - electricity

• I-V characteristics- PD


  potential difference (V)

  measured in volts
• I-V characteristics- FL


  filament lamps

  as temp increases, resistance increases

  
• I-V characteristics- D


  diodes

  current can only flow in one direction

  
• I-V characteristics- OC


  ohmic conductors

  resistors- resistance stays consistent

  applies at constant temp

  current is directly proportional to potential difference

  
• static electricity- electrons


  rubbing insulating materials together rubs electrons off one material and onto another

  material gaining electrons becomes negatively charged
• static electricity


  charged object produces an electric field around itself

  field lines point from positive to negative
• mains electricity- EW


  earth wire

  green and yellow stripes

  prevents appliance from becoming live
• mains electricity- NW


  neutral wire

  blue

  completes the circuit
• mains electricity- LW


  live wire

  brown

  mains electricity voltage is 230V
• national grid- PL


  power lines

  transports current at a very high voltage

  higher voltage reduces energy loss
• national grid- S-DT


  step down transformer

  voltage decreases

  used between power lines and houses
• national grid- S-UT


  step up transformer

  voltage increases

  used between power stations and power lines
• circuit arrangement- AC


  alternating current

  direction of current flow continually changes
• circuit arrangement- PC


  parallel circuit

  current is split between branches

  potential difference across each branch is the same

  ($1/R=$$1/R1+$$1/R2$)
• circuit arrangement- SC


  series circuit

  current is constant

  (R=R1+R2)
• circuit arrangement- DC


  direct current

  current flows in one direction
• electrical conductors and quantities- C(Q)

  charge (Q)

  measured in coulombs

  can only flow if there is a source of potential difference

  (E=QV)(Q=It)
• electrical conductors and quantities- R(R)

  resistance (R)

  measured in ohms

  how hard it is for current to flow
• electrical conductors and quantities- C(I)

  current (I)

  measured in amps

  the rate of flow of charge

  (V=IR)
• electrical conductors and quantities- P(W)


  power (W)

  measured in Watts

  rate of energy transfer

  (E=Pt)

  ($P=$$I^2R$)(P=IV)