In a transistor radio receiver, the function of a transistor is to amplify alternating current signals, which is done by varying the amount of metal on two sides of a small conducting strip called an oxide.
By doing this, some electrons flow through one side of the conducting strip and some flow through the other and into an antenna. The transmitter in your car works similarly.
In fact it’s more like your home stereo system because in your home stereo system you also have speakers that can only produce sound when there are electrons passing through them! In order to make sure that all components act properly, there needs to be electron flow from one component to another.
Electrons are very small and it is difficult to control their flow. Engineers use transistors to control the flow of electrons. Since they do this by controlling which sides of the conducting strip take in excess electrons, transistors are called Switching Devices (or Semiconductor Switchers).
Electrons are either added or taken away from a transistor, depending upon the strength of the current. The stronger the current, the bigger it gets and the more excess electrons are added. In other words, transistors work by switching on and off.
There are many different transistors. Some work in AM radios and some in FM radios. The metal in your transistor is probably a combination of aluminum oxide and barium oxide. Baeyer metal is similar to what you have but has tin oxide instead of barium oxide.
It is really cool that engineers control whether electrons flow through your transistor by using sound waves generated by your radio station! That’s right, when you hear the song on the radio, there is actually a transmitter in your radio station sending electrical signals to your transistor (transmitting its sound).