Close the Loop

Lesson 1 of 10 · 5 min · Free, no account needed

What you will learn

A bulb lights only in a closed loop: from the battery's + end, through the bulb, and back to its minus end.
Charges are in the wires all along. Close the loop and they all start moving at once, all the way round.
Conductors (metals, pencil lead) let charge through; insulators (plastic, rubber, wood) do not.

One battery, one bulb, one wire. Can you make it light?
Drag from a dot to draw your wire. You only get one.
Now use as many wires as you like. Light the bulb.
Watch the blue dots when it works.
Which things can close the loop?
Test each object in the gap, then drag it to its pile.
In a conductor some charges are free to move, so a push from the battery makes them flow. In an insulator the charges are held in place, so the loop stays open.
The words for what you just built.
A circuit is a path that charge can flow around.
It works only as a closed loop: from the battery's + end, through the bulb, back to its minus end. One break anywhere and everything stops.
Conductors let charge through (metals, graphite). Insulators do not (plastic, rubber, wood, air).
Game: Light them all. Light every bulb with as few wires as you can.
One wire is one stroke of your finger, any length. Beat par for 3 stars.
The power is off. Tap every bulb that will light when it comes on.
Charge must flow through a bulb: in at one contact, out at the other, and on round the loop. A bulb joined by only one contact is a dead end.
Your two-bulb circuit from the game. Switch it on.

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