Some lamps are used for lighting—that is, for illumination. In a circuit diagram, these are indicated by a circle around the wire, with a smooth, half-oval bend in the wire line inside the circle.
Other lamps are meant only as indicators. An example would be the “on” light on a stove or coffee maker. These are also indicated by circles, except the circles have large X’s inside them. The wire line is not drawn through indicator lamp circles.
A heater takes the electricity in a circuit and radiates it out from the circuit as heat. A heater is indicated by a rectangle drawn along the wire line with its long sides parallel to the wire. The wire line does not continue through the rectangle. Instead, three lines are drawn inside the rectangle, parallel to its short sides.
A motor uses the electricity in the circuit to power some motion. A motor is indicated by a circle on the wire line with a capital M inside it.
A bell uses the circuit’s electricity to make a ringing sound. A bell is indicated by a half-circle. The circuit wire runs into the flat side of the half-circle, and also exits through the flat side.
A buzzer uses the circuit’s electricity to make a “buzz” sound. Like a bell, a buzzer is indicated by a half-circle. The difference is that the circuit wire enters and exits the bell via the curved side of the half circle.
An inductor is a coil of wire that causes a magnetic field as current passes through it. An inductor in the circuit is indicated by a section of squiggly line in the straight wire line.