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.
Instructions. Click the Apple logo from the Finder menu. Click System Preferences.. Click Sound.. Click the Internal Microphone option under Select a Device for Sound Input.. The MacBook's microphone is now set to turn on whenever you launch an application that uses sound, such as GarageBand or iChat. The built-in microphone is located above the Esc key on the MacBook's keyboard.