A chemical property is a characteristic of a pure substance that describes its ability to change into different substances. For example, a chemical property of methane is that it can catch fire and burn in air. Physical properties can be observed or measured without changing the composition of matter.
The downsides are obvious: Almost everyone has headphones, speakers, and other gadgets based on the ubiquitous 3.5 mm headphone jack. Eliminating this connection could render these devices unusable, or at least force everyone to carry around an extra adapter. But Apple doesnât care.
The headphone jack is another name for the audio output. So the headphone jack on your iPod is outputting the audio to your headphones that receive the audio to play it through the tiny speakers. The microphone jack is another name for the audio input.