Describe briefly how a robotic arm with a revolute joint is controlled by a motor.

In a robotic arm with a revolute joint, the sensors first provide input about the position and orientation of the arm to the controller. The controller processes this input and generates control signals using control algorithms. These signals are sent to the actuator, which is an electric motor. The motor converts the electrical signal into mechanical motion, producing the rotational (angular) movement of the revolute joint. A feedback mechanism monitors the movement so that the arm reaches the desired position accurately.