-- The long line and short line close together at the left side of the diagram represent a single-cell battery. It's the only one in this diagram. It's a device that stores chemical energy and delivers it on demand.
-- The zig-zag lines with circles around them represent light bulbs. There are three of them in this diagram. They are devices used to produce light by dissipating electrical energy.
-- The zig-zag lines without circles, at the top of the diagram, represent resistors. There are two of them in this diagram. They are devices used to change or control electrical parameters within a circuit by dissipating electrical energy.
-- The short straight line between two small circles at the bottom of the diagram represents a switch. There is only one switch in this circuit. It's a device used to easily and quickly start or stop the flow of current past a certain point in a circuit.
In this circuit ...
-- When the switch is closed (as drawn), the light bulb nearest the battery glows brightest, the light bulb in the middle glows less bright, and the light bulb on the right side glows dimmest of all.
-- When the switch is open, the light bulb nearest the battery glows, and neither of the other two light bulbs glows at all.
