what is a relay used for?

[vroo//M]

I opened up my fuse box to replace a few fuses before installing my new 100w ellipsoids, and whoa! I can't find the lowbeam relay (either K46 or K48); the highbeam relay was there though. There is an empty slot with buncha cables below where the lowbeam relay should be. Yet my lights are functioning normally though. The 100w ellipsoids are awesome....

I noticed that not all the fuse slots are filled.... should they be?
Is it okay to go without this relay? and what are relays for anyway?

Erwin

[nodemgr]

A relay takes a small voltage difference, say an output from a computer, and uses that to switch on or off a higher power output, say to your headlights. This way your computer doesn't have to put out X volts and have Y amps running through itself. The higher potentional is residing at the relay.

When you hear a relay click you are actually hearing the high power contacts connect and separate due to an electromagnet.

[UD///M]

Not only do they allow switching a higher voltage with a lower voltage but also they allow switching a higher current circuit with a low power circuit. Power is the key word since it is the product of voltage and current.

Relays have two power ratings. One is for the control voltage and current and the second is for the switched voltage and current.

[Atticka]

now I understand.....:)

thats kinda cool....so when you turn your lights on, the power isnt running through the switch, rather the switch you turns on a relay....neato!