X-rays are commonly produced by accelerating (or decelerating) charged particles; examples include a beam of electrons striking a metal plate in an X-ray tube and a circulating beam of electrons in a synchrotron particle accelerator or storage ring.
Examine your computer for jacks and ports that support your audio device. The location of certain jacks and ports will vary depending on your computer's make and model. For example, most jacks on a desktop computer will be located in the back; whereas jacks on a laptop computer are usually located on its sides.
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.