Is my analogy correct:
With a highway as an example, would
- Resistance (ohms) be the number for lanes in one direction
- Current (amps) be the density of cars on the road
- Voltage (volt) be the speed limit of the road
What I find confusing is current and voltage. Current, if it can relate to density, could be a factor of voltage?
Answer
Your analogy is quite good. It shows however a slight misconception about electron movement in conductors.
Electrons in conductors are not cruising along like cars on a road. It is more like bumper cars: they continuously accelerate, hit a obstacle, are stopped & deflected and begin again to accelerate. Also, the density of electrons is always the same.
A better picture would be this: Imagine a high-way with walls on the sides so cars cannot escape. The problem is, all over the road grows a forest with trees (i.e. atoms). The cars are pulled through the forest by bungee cords attached to the battery at the other end and continuously keep bumping into the trees.
- Conductor: the highway with walls and a forest growing on the road. It is always filled to the brim with cars.
- voltage: the tension in the bungee cord. It will not really make the cars travel through the forest faster as they still keep bumping into trees. It makes these collisions however a lot stronger.
- resistance: the opposite of the width of the highway. The width itself would be conductivity.
- current: the amount of cars going through the highway in a given time. Wider highway (i.e. less resistance) --> more cars.
That being said, there cannot be an exact analogy. Even mine has issues. How you best set up the analogy depends on what aspect of electricity you want to illustrate. It is unavoidable that other aspects are presented in a slightly skewed fashion.
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