Resistors:
A resistor resists the flow of electrons. It can be used to change the voltage or current in a circuit. They are measured in ohms (W) and coded by color. See the figure below:
Bulbs:
A bulb resists the flow of electrons. Since the electrons have to do work to move through the wire, the wire becomes heated. When it is heated to a high enough temperature, it will radiate visible light. Bulbs are typically only a few ohms in resistance.
Speakers:
A speaker changes electric oscillations into magnetic oscillations which in turn oscillate a cone which makes the air vibrate which oscillates your ear drum which stimulates the optic nerve which makes you hear. A typical speaker has a resistance of 8 W.
Capacitors:
There are two kinds of capacitors:
The ceramic capacitors (usually disk shaped) have no polarity and may be connected in any fashion.
The electrolytic capacitors (usually cylinder shaped) have to observe strict polarity. They typically have a line down the side indicating which side should be connected to positive (+). This line indicates the flow of electrons, which is to the positive terminal.
Breadboard:
The solderless breadboard is an easy way to make electric circuits. The diagram below indicates how it should be used:
Diodes and LEDs:
Diodes and LEDs (Light Emitting Diodes) observe strict polarity. Typically, the short side or flat side should be connected to the ground for an LED and the side with the stripe should be for a diode. See the diagram below:
Transistors:
Transistors use a small amount of current to control a large amount of current. As such, they can be used as on or off switches. Transistors come in two types, based on how the semiconducting layers are set up: npn or pnp type. They contain three leads. One is called the emitter (E), one is the collector (C), and the third is the base (B). Different applications will observe different polarity, but care must be taken to place EBC where they should be and not allow them to be switched. Normally a transistor provides very high resistance between the collector and the emitter; it allows no current through. However, once there is a small current through the base to the emitter, the resistance between the collector and emitter plummets, allowing current to flow. See the figure below:
Integrated Circuits (IC Chips):
IC Chips are pieces of silicon that contain several resistors, capacitors, diodes, transistors, etc. The pins (pinouts) are labeled by number, which typically starts with a notch or hole near the top of the IC and counts counterclockwise beginning at 1. See the figure below:
