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 "dim...
Electromechanical Relay An electromechanical relay is a type of relay which function using a magnetic field produced by an electromagnetic coil when a control signal is applied to it. It is called as electromechanical since it has moving contacts in the output circuit which are operated by applying an electrical signal. Working Principle An electromechanical relay transfers signals between its contacts through a mechanical movement. It has three sections viz. input section, control section and output section. The input section consists of input terminals where a small control signal is to be applied. The control section has an electromagnetic coil which gets energised when control input signal is applied to the input terminals and the output section consists of an movable armature and mechanical contacts – movable and stationary, the movement of the armature makes or breaks the electrical circuit. When an input control voltage is applied to the electromagnetic coil, it gets magnetised ...