Final answer:
An electric generator is a device that converts mechanical work into electric energy by rotating a coil within a stationary magnetic field.
Step-by-step explanation:
A device consisting of a coil that is mechanically rotated in a stationary magnetic field is called an electric generator. This device converts mechanical work into electric energy by inducing an electromotive force (emf) when the coil is rotated within the magnetic field.
This principle is applied in various electromechanical devices such as motors where a rotating coil produces a back emf which opposes the input emf, and in medical instruments like an MRI machine which uses a superconducting cylindrical coil to produce a main magnetic field.