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HEADLIGHT

 Headlights



Most cars have two head-lights with both upper and lower beams. They are mounted at the same level and at an equal distance from the centre of the vehicle. A headlight consists of a housing, the reflector, the light diffusing glass and the bulbs along with their sockets. The reflector concentrates the light, which is emitted by the bulb in all directions and then directs it ahead of the vehicle. The reflector is paraboloid in shape and its reflecting surface is "silvered", usually a thin coating of aluminium and protected by a thin film of quartz.


The bulb consists of a coil or "coiled-coil" filament. The fixing tabs on the base of the bulb are located in such a way that the filament is accurately located at the focus of the reflector. Actually the bulbs are of the filament type with a built-in screen. The first filament i.e. for high beam or "far beam" is placed at the focus of the reflector. The other filament i.e., for low beam or "dimmed light" is located a little in front of the focus and slightly above. The light emitted by low beam filament is reflected in the form of downward directed spreading beam. Rays from the filament, which strike the lower part of the reflector are intercepted by the screen and so there is no upward directed spreading beam.

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