Electric fans rotate due to the principles of electromagnetic induction and the design of the electric motor within the fan. The core keyword, "Electric Fan Rotation," refers to the motion of the fan blades, which is a result of the interaction between an electric current and a magnetic field.

In more detail, an electric fan operates based on the principle of electromagnetic induction. When an electric current flows through the copper wires wound around the stator (the stationary part of the motor), it creates a magnetic field. This magnetic field interacts with the permanent magnets or electromagnets in the rotor (the rotating part of the motor), causing the rotor to spin. The fan blades are attached to the rotor, so as the rotor spins, the blades rotate, creating air movement.

According to the National Electrical Manufacturers Association (NEMA), the efficiency of an electric fan is largely determined by the design of the motor. For instance, a fan with a high-efficiency motor, such as an Energy Star-certified model, can use up to 50% less energy than a standard fan. This efficiency is achieved through the use of advanced motor technology that minimizes energy loss during operation.

The design of the fan also plays a crucial role in its rotation. The blades are shaped and positioned in a way that optimizes air flow. The angle and length of the blades are carefully calculated to ensure that the fan produces a strong, steady airflow. For example, a fan with curved blades can move more air than a fan with straight blades of the same size, as the curved shape helps to push the air more efficiently.

In conclusion, electric fans rotate due to the electromagnetic induction principle and the efficient design of the motor and blades. The interaction between the electric current and the magnetic field in the motor causes the rotor to spin, which in turn makes the fan blades rotate, creating air movement. Advanced motor technology and blade design further enhance the efficiency and effectiveness of electric fans.