| A type of device that uses an electromagnetic field to accelerate charged particles in a straight beam towards a target. Linear Accelerators are found in small, medium, and enormous applications.
The small application is simply the cathode ray tube found in most television sets and monitors. Electrons are emitted by a hot cathode, then accelerated into a beam, which is then dispersed to a phosphor screen.
The medium application is found in hospitals, and is used in radiation oncology to zap cancerous tumors. Electrons are accelerated towards a metal plate, which emits X-rays as a result of the impact.
The enormous application is the Stanford Linear Accelerator Center, which creates a field a few kilometers long, which can put enough momentum into a charged particle to create effects interesting to physicists when said particle hits a target. | 
