deflection coil

In television technology, deflection coils are crucial components within cathode-ray tubes (CRTs). These electromagnet coils are precisely designed to control the electron beam's path, ensuring the scanning spot remains in focus across the screen.1

The principle behind deflection is that an electron moving through a magnetic field experiences a force perpendicular to both its motion and the field lines. By passing the electron beam through the magnetic field generated by the deflection coils, its direction is altered. The current flowing through these coils dictates the strength of this force, thereby controlling the beam's deflection.1

These coils are typically arranged in a structure called a deflection yoke, which surrounds the neck of the picture tube. The precise control of current in both horizontal and vertical deflection coils allows for the creation of the image displayed on the screen.1