 This video we're going to just walk through a quick simple diode calculation. I have two diodes here I've got that diode there. I've got that diode there. I've got a bunch of resistors in here We're going to see what happens with the current in here We're going to see what happens with our total circuit resistance So take a walk with me if you will in this circuit here You'll notice that if my current if we're using Electron current flow flows from negative to positive So current is going to flow across this guy here because this is forward bias Which means that current wants to go through here more than it wants to go across the 30 ohm resistor for all intents and purposes, we're just going to say all the current is flowing across the The diode right now. There's going to be some there, but we're not going to get too into that Don't worry about it. So we got current flowing across there. It's going to go across the 40 ohm resistor Come along here. It's going to get blocked by that diode So it's going to end up going across 20 ohms and 10 ohms and back to the positive So if I wanted to add up to figure out what my current is going to be I'm going to add 40 plus 20 is 60 plus 10 is 70 I'm ignoring this guy because basically this Diode here acts like a jumper across the 30 ohm resistor So I have 70 ohms of resistance that I'm dealing with to determine the current in this circuit So now I'm going to figure out what my volt drop or my current in this circuit is now I have 48 volts here. You'll notice up here. I've got 47.3 That's because we need to take into account that this diode here is going to have a 0.7 volt drop across it And if you've watched the other videos on the PN junction dial, you'll see why that is But in this case if this is a silicon diode, I've got a 0.7 volt drop across here So I have to take that into account So therefore I'm going to be dealing with 70 ohms across this is going to have the rest of the voltage 47.3 volts divided by 70 ohms tells me that there's going to be 676 milliamps flowing through this circuit again 48 minus 0.7 gives me 47.3 I have current flowing across 70 ohms of resistance 47.3 divided by 70 gives me 676 milliamps There we go Now if I'm trying to determine the actual circuit total resistance not just the 70 but taking this diode as well into account I would do this. I would take the 48 volts of total circuit voltage and divide it by 676 milliamps and that will give me my total circuit resistance In this case, it's a little more 71 ohms See it's not just the 70 ohms that we had here because we have to take this into account And therefore my total resistance in the circuit is 71 ohms with the diode included