An electric fan rotates due to the interaction between the electric motor's stator and rotor. When electricity is supplied to the motor, the stator creates a rotating magnetic field. This field induces a current in the rotor, which in turn generates its own magnetic field. The interaction between these magnetic fields causes the rotor to spin, thereby rotating the fan blades.

The rotation of an electric fan is primarily driven by the design and construction of the electric motor. The motor typically consists of a stator, which is a stationary part with coils of wire, and a rotor, which is a rotating part with permanent magnets or electromagnets. When an electric current flows through the stator coils, it creates a magnetic field. This magnetic field interacts with the rotor's magnets, causing the rotor to rotate. The speed of rotation is determined by the frequency of the electrical supply and the design of the motor.

According to the U.S. Department of Energy, the efficiency of an electric fan is influenced by factors such as the motor design, blade shape, and airfoil design. A well-designed motor with efficient coils and magnets can convert more electrical energy into mechanical energy, resulting in a more effective fan. For instance, a fan with a motor efficiency of 80% will convert 80% of the electrical energy into kinetic energy, while the remaining 20% is lost as heat.

Moreover, the blade design plays a crucial role in the fan's performance. The shape and angle of the blades are optimized to minimize aerodynamic drag and maximize airflow. A study by the Lawrence Berkeley National Laboratory found that fans with aerodynamically designed blades can provide better air movement and efficiency compared to those with less optimized designs.

In conclusion, the rotation of an electric fan is a result of the electric motor's design and the interaction between the stator and rotor. Efficient motor design and optimized blade shapes contribute to higher efficiency and better air movement. The U.S. Department of Energy and the Lawrence Berkeley National Laboratory provide valuable insights into the factors that influence fan performance and efficiency.