How can sound still play if only one wire is connected to the radio?

It is not possible for sound to play if only one wire is connected to the radio. In order for sound to be played, there must be a complete circuit between the radio and the speaker. This circuit consists of two wires, one positive and one negative. When the radio sends an electrical signal through the positive wire, the speaker receives the signal and converts it into sound. If only one wire is connected, the circuit is incomplete and the sound cannot be played.