magnetism

• Resistance


  Voltage/current
• Power (electrical)


  Current x voltage
• Energy


  Power x time
• Resistors in series


  R1 + R2 = Rt
• Potential dividers


  V1 = (R1/R1+R2) x V
• Transformers


  Vp/Vs = Np/Ns
• Transformers (at maximum efficiency)

  VpIp = VsIs
• I current


  Q / t
• Power loss


  I^2 x R
• Power (voltage, resistance)


  V / R
• Series voltage (emf shared)


  Vsource = V1 + V2
• Series current


  I1 = I2 (same current)
• Voltage parallel

  Vsource = V1 = V2 (same emf)
• Current parallel


  I source = I1 + I2 (current shared in pathways)
• Voltage (emf, pd)

  Workdone / Q
• potential divider (ratio)


  R1/R2 = V1/V2