The resisting

Ropes, bulbs and resistance

Grab more, and you exert a bigger slip force on the rope. That resists the flow of the rope. The flow of the rope gets smaller.

Just like any other slip force, the bigger the force, the more it resists movement.

Replacing one bulb with a different bulb that resists more makes the electrical current smaller. You put something different in the loop. The new bulb has a bigger resistance.

Every bulb has an electrical resistance. This resistance is a certain number of ohms. Use the number of ohms to predict how much the current is resisted.

Resistors and controlling flow

Controlling the flow of electricity is so important that there are resistors as well as bulbs. Bulbs should glow. Resistors only resist. Resistors control the current: they control the flow.

Resistance and rope loops

A switch is a very special resistor: use the switch to go between an enormous resistance and no resistance. So opening a switch is like grabbing the rope loop so hard that it cannot move: the rope might as well be cut, breaking the rope loop. A switch does just that: it breaks the electrical loop.

You can put different resistors into circuits. The larger the resistor, the more it resists the current.

You find electrical loops everywhere because control of the current is not too hard.