Relay, SPDT

hi this dr. class here and in this video I will talk about relays and if you've been following my channel I've done some videos on installing car alarms car stereos hid installs and in those videos I talked about using relays and for those of you who are not familiar with it this video will help explain how it really works how to choose the relay that you want to use for your application so in front of me these four little devices you see are all relays as you can see they come in different shape size color packaging relays are essentially switches that you can turn on and turn off by applying electricity to a coil inside the relay when you energize that coil you'll create a magnetic field they'll attract that metal contact to mechanically close that switch when you take away the power source to the coil the magnetic field is gone and then the switch will open up the game when you're lo