The circuit or device that supplies signal power or electric energy or charge to a transducer or load circuit.

The terminal in a field-effect transistor from which majority carriers flow into the conducting channel in the semiconductor material.

A radioactive material packaged so as to produce radiation for experimental or industrial use.

1. In general, a device that supplies some extensive entity, such as energy, matter, particles, or electric charge.

2. A point, line, or area at which mass or energy is added to a system, either instantaneously or continuously.

3. A point at which lines of force in a vector field originate, such as a point in an electrostatic field where there is positive charge.

The arc or spark that supplies light for a spectroscope.

A device that supplies heat.