Relay

relay sues a low amperage circuit to switch on a higher amperage circuit.
we are done by making realy circuit at the class.

There are very common on vehicles and there are many types of relays but they are very similar in how they work. the diagram above is one of the relay procedure on the car..

we were making parallel circuit with 3 bulb and check the voltage drop.
86, is input position so no matter switch is on and off, there will be always 12 volts.
85, when "on"switch opsition, the coil starts consuming the voltage which available voltage dropped as 0volt.
30 is the low amperage but another input position so always 12volts available.

87a. when the switch is off, the switch connect to the 87a so that 12volt goes through here until switch on position.