When we want to tell someone about an electrical device we have made, we need to specify what is connected to what, and how. This is most easily done using a pictoral language, in which the electrical components are reduced to simple sketches. The elements of this language are given in the table below. It is assumed that the wires are covered with an insulator (colored plastic, in the case of the wires in your kit). Then wires that cross each other don't make a new conducting path.

component name	representation
battery (A)
wire (B)
intersecting wires
nonintersecting wires (C)
motor (D)
light bulb (E)

Now let's try to use this language:

• The simplest possible electrical device is . It doesn't seem to do anything, but actually it is running down the battery as fast as it can! This is called a "short circuit," because the most common way for it to happen is to have two wires touch accidentally, giving the current a short cut. We all make this circuit a few times when we are first learning about electricity. If you make this circuit, don't leave it hooked up more than a few seconds -- your battery will go dead after a while.

• You have already made this diagram: by connecting the wires of the motor to the corresponding parts of the battery. Since the motor has its own wires, we don't need to introduce any; but you could add some of the wires from the kit, as shown in the picture. Note that the diagram doesn't try to represent the actual shapes and lengths of the wires. It tries to indicate the path that the current takes, and as simply as possible. Using two wires or four wires or seventeen wires to connect the motor to the battery would give the same diagram.

  This diagram is an example of the central concept in electricity: the electrical circuit. The battery tries to push "the electrical fluid" out the positive end, but cannot do anything unless there is someplace for the "fluid" to go; and it also needs a supply of the "fluid." We accomplish this by connecting the two ends of the battery through a path of wires and other electrical components. This provides a complete path from one end of the battery to the other, along which current can flow. When a current is flowing, the battery is giving energy to the circuit, and this energy is delivered to the components in the circuit.
• To build on the concept just introduced, you should consider the devices shown below. None of them is very interesting; only one of them does anything at all! Decide what you think is wrong with each diagram, and then click on it for another opinion.

Diagrams are a way to communicate how a circuit is put together. One way to turn a diagram into an actual circuit is to redraw the diagram on a full-sized piece of paper, place each component where the diagram indicates, and then connect them together with wires that run along the lines.

Check the box when you are done:  
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