Don't take these too literally, but they are illustrative and suggestive.

Quantity | Symbol | Units | What it is | Analogue | Units |
---|---|---|---|---|---|

Charge | q | Coulombs | Electric charge | Water | Gallons |

Current | i=dq/dt | Amperes= coulomb/sec | Flowing charge | Water flow | Gallons per second |

Voltage | v | volts | Elec. potential | water pressure | psi |

Resis- tance | R=v/i v=iR | Ohms | need a field to move a charge |
Resistance | Pressure drop:pipe |

Conduc- tance | G=i/v G=1/R | Mhos (read backwards) | need a field to move a charge | conductance | Pressure drop:pipe |

Ideal wire | R=0 | 0 Ohms | superconductor | Ideal pipe | no friction |

Voltage source | V_{s} | v=constant | ideal battery or ideal generator | constant pres- sure pump | water tower |

Current source | I_{s} | i=constant | ideal solar cell | constant velo- city pump | fountain |

Capacitor | i= Cdv/dt | Farads | Stores separ- chargeated |
Water tower (stores water) | Gallons, or height |

Inductor | v= Ldi/dt | Henrys | Links mag- netic field |
None | None |

Energy | W=qv | Joules | To move charge across voltage |
Potential energy | PE=(mg)h |

Another perspective, using height instead of pressure as analogous to voltage:

Quantity | What it is | Water Analogue |
---|---|---|

KCL (current law) | conservation of charge | water flow in=water flow out |

Negative current | actual flow other way | actual flow is the other way |

Resistors in series | R=R1+R2 | Resistance increases w/length |

Resistors in parallel | G=G1+G2 | Pipes in parallel increase flow |

Voltage (another way) | Electrical potential | Height (gravitational potential) |

Kirchhhoff's (KVL) Voltage Law | potential is path-indpt in electric circuits |
takes same energy to reach a height regardless of path |

Ground potential | Reference voltage | Sea level |

Node voltage | Voltage at a point | Height above sea level |