I) structure. Automobile headlight: it is generally composed of bulb, reflector and matching mirror.

2) Working principle. Take double filament headlight as an example to illustrate its working principle.

The near-light filament is located in front of the focus, and the light emitted by the filament is inclined to the ground after reflection. The lower part of the short-light filament is also equipped with a hood, so that the reflector does not reflect upward light, which has the effect of anti-glare but the irradiation distance is short; The high light filament is located at the focal point of the reflector. The light reflected by the mirror will emit its beam parallel and far away. However, the light will be directly into the eyes of the driver on the opposite side, causing a glare.

(2) Light switch Modern cars used more is the headlight, taillight, turn signal and light switch made into an integrated combination of switches. The form of light switch has a variety of forms such as push-button type, rotary type and combination type.

(3), the structure and lead terminals of the contact normally open headlight relay are shown in the headlight relay. Terminal SW is connected to the headlight switch, terminal E is connected to the iron, terminal B is connected to the power supply, and terminal I is connected to the light switch.

When the headlight switch is switched on, the relay core is electrified, the electric shock is closed, and the power is supplied to the headlight through the light changing switch.