... like I'm 5 years old
A radio is a device that receives and broadcasts audio signals. It's like a messenger that delivers messages from one place to another. Let's imagine you're at a party and you want to deliver a message to your friend at the other end of the room. You could shout, but that would be too noisy and disruptive. Instead, you give your message to a friend who is going in that direction, and they deliver it for you. That's what a radio does with sound. It picks up signals (the message), sent through the air, and delivers them to your radio speaker (your friend), which then produces the sound (delivers the message) for you to hear.
An analogy for a radio is a messenger in a noisy room. It picks up messages (signals) sent through the air and delivers them to your speaker, which produces the sound for you to hear.
... like I'm in College
A radio works by receiving radio waves (a type of electromagnetic wave) and converting them into sound. The process starts when a radio station broadcasts a signal. This signal is sent out as radio waves which travel through the air at the speed of light. Your radio receiver picks up these waves with its antenna. Inside the radio, these waves go through a process of conversion. They are first filtered to separate the desired frequency, then the signal is amplified, and finally, the signal is demodulated, converting it back into an audio signal. This audio signal is then sent to your radio's speakers, where they are converted into sound.
Imagine you have a box full of different colored Lego bricks, each color representing a different radio station. Now, you want to build a model using only the red bricks (tuning). You pick out all the red bricks, but they are too small to build anything substantial (weak signal). So, you decide to use more red bricks to increase the size of your model (amplification). Now, you have a big pile of red bricks, but they're all mixed up (modulated signal). You sort them by size and shape (detection), and then use them to build your model (reproduction).
This is similar to how a radio works - it selects a specific frequency (color), amplifies it (adds more bricks), demodulates it (sorts the bricks), and finally converts it into sound (builds the model).
... like I'm an expert
The functioning of a radio is a matter of electromagnetic theory and signal processing. Radio broadcasting relies on the phenomenon of electromagnetic radiation, wherein energy is transmitted through space in the form of waves. These waves, specifically radio waves, carry the audio signal encoded in a specific modulation scheme.
Radio receivers perform four primary actions - tuning, amplification, detection, and reproduction. Tuning is the process of filtering out the desired frequency from all the radio waves the antenna receives. Amplification boosts this weak signal to a higher energy level suitable for detection. In the detection stage, the modulation applied at the transmitter is removed to reveal the original audio signal. This signal is then transformed into sound waves by the loudspeaker in the reproduction stage.