[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:01.30,0:00:04.35,Default,,0000,0000,0000,,Now, let's talk about measuring\Nresistance and voltage.
Dialogue: 0,0:00:04.35,0:00:09.24,Default,,0000,0000,0000,,This device right here is an ohmmeter and\Na voltmeter.
Dialogue: 0,0:00:09.24,0:00:14.13,Default,,0000,0000,0000,,So here's how I will measure resistance or\NI can measure DC voltage,
Dialogue: 0,0:00:14.13,0:00:16.59,Default,,0000,0000,0000,,or I can measure RMS, AC voltage.
Dialogue: 0,0:00:16.59,0:00:20.77,Default,,0000,0000,0000,,Today, I am interested in measuring\Nohms and measuring volts.
Dialogue: 0,0:00:20.77,0:00:26.02,Default,,0000,0000,0000,,So what I have built is a series circuit\Nwhere I have four resistors and series.
Dialogue: 0,0:00:26.02,0:00:27.90,Default,,0000,0000,0000,,1k, 3k, 4k and 5k.
Dialogue: 0,0:00:27.90,0:00:31.05,Default,,0000,0000,0000,,They'll be connected to a three-volt\Nsource which you don't see yet.
Dialogue: 0,0:00:31.05,0:00:33.65,Default,,0000,0000,0000,,In this device right here,\Nthis is a protoboard and
Dialogue: 0,0:00:33.65,0:00:36.14,Default,,0000,0000,0000,,I've connected this\Ncircuit on my protoboard.
Dialogue: 0,0:00:36.14,0:00:40.81,Default,,0000,0000,0000,,The way a protoboard works is\Nevery row is an individual node.
Dialogue: 0,0:00:40.81,0:00:44.87,Default,,0000,0000,0000,,So this is a node, this is a node,\Nthis is a node and so on.
Dialogue: 0,0:00:44.87,0:00:48.36,Default,,0000,0000,0000,,When you cross this plastic barrier,\Nhere is a new node.
Dialogue: 0,0:00:48.36,0:00:49.66,Default,,0000,0000,0000,,Here is another node.
Dialogue: 0,0:00:49.66,0:00:51.79,Default,,0000,0000,0000,,Here is a third node and so on.
Dialogue: 0,0:00:51.79,0:00:55.53,Default,,0000,0000,0000,,So I have my 1k resistor\Nconnected through this node.
Dialogue: 0,0:00:55.53,0:00:58.84,Default,,0000,0000,0000,,This is actually the green\Nnode connecting to the the 3k.
Dialogue: 0,0:00:58.84,0:01:02.51,Default,,0000,0000,0000,,The 3k is connected to the 4k\Nwith the blue node and
Dialogue: 0,0:01:02.51,0:01:06.10,Default,,0000,0000,0000,,the 4k is connected to\Nthe 5k at the yellow code.
Dialogue: 0,0:01:06.10,0:01:08.79,Default,,0000,0000,0000,,The 5k is going to be connected\Nto the negative side of
Dialogue: 0,0:01:08.79,0:01:11.68,Default,,0000,0000,0000,,my voltage through the black node,\Nwhich is right here.
Dialogue: 0,0:01:11.68,0:01:14.01,Default,,0000,0000,0000,,That is this whole line and\Nthe red node or
Dialogue: 0,0:01:14.01,0:01:18.07,Default,,0000,0000,0000,,the positive three-volt source is\Ngoing to be connected right here.
Dialogue: 0,0:01:18.07,0:01:23.11,Default,,0000,0000,0000,,Now if I want to measure resistance, I am\Nnot going to have my source connected,
Dialogue: 0,0:01:23.11,0:01:27.64,Default,,0000,0000,0000,,because that may end up being in series or\Nparallel with my resistance.
Dialogue: 0,0:01:27.64,0:01:29.49,Default,,0000,0000,0000,,So I'm not going to put that there, but
Dialogue: 0,0:01:29.49,0:01:31.90,Default,,0000,0000,0000,,I want to just measure my\Nresistors by themselves.
Dialogue: 0,0:01:31.90,0:01:36.72,Default,,0000,0000,0000,,So I'm going to touch one side of my\Nlead to one side of the resistor.
Dialogue: 0,0:01:36.72,0:01:38.91,Default,,0000,0000,0000,,The other side will lead to\Nthe other side of the resistor.
Dialogue: 0,0:01:38.91,0:01:43.64,Default,,0000,0000,0000,,And look, this is 0.987 kiloohms\Nwhich is just about 1k.
Dialogue: 0,0:01:43.64,0:01:46.90,Default,,0000,0000,0000,,These are five percent resistors,\Nso that's good.
Dialogue: 0,0:01:46.90,0:01:48.80,Default,,0000,0000,0000,,Now, let's measure our 3k resistor.
Dialogue: 0,0:01:48.80,0:01:51.31,Default,,0000,0000,0000,,Touch one side, touch the other side.
Dialogue: 0,0:01:51.31,0:01:53.78,Default,,0000,0000,0000,,There's what my 3k resistor looks like.
Dialogue: 0,0:01:53.78,0:01:55.38,Default,,0000,0000,0000,,Here's the 4k.
Dialogue: 0,0:01:55.38,0:01:57.33,Default,,0000,0000,0000,,One side touch the other side.
Dialogue: 0,0:01:57.33,0:02:02.49,Default,,0000,0000,0000,,There's my 4k and here is my 5k resistor.
Dialogue: 0,0:02:02.49,0:02:06.04,Default,,0000,0000,0000,,Okay, now let's hookup\Nour three-volt source.
Dialogue: 0,0:02:06.04,0:02:09.62,Default,,0000,0000,0000,,The three-volt source is going to\Nbe from two batteries in series.
Dialogue: 0,0:02:09.62,0:02:12.74,Default,,0000,0000,0000,,I'm going to connect the red\Nside right there and
Dialogue: 0,0:02:12.74,0:02:15.40,Default,,0000,0000,0000,,the black side right there to my circuit.
Dialogue: 0,0:02:15.40,0:02:20.12,Default,,0000,0000,0000,,All right, now let's measure the voltage\Nacross this three-volt source.
Dialogue: 0,0:02:20.12,0:02:25.04,Default,,0000,0000,0000,,And actually, I have a couple little\Npins here that are just going to help
Dialogue: 0,0:02:25.04,0:02:27.54,Default,,0000,0000,0000,,me be able to hold my things in place.
Dialogue: 0,0:02:27.54,0:02:32.30,Default,,0000,0000,0000,,So here is a little pin that's going to\Nallow me to connect my black loop there,
Dialogue: 0,0:02:32.30,0:02:36.55,Default,,0000,0000,0000,,I made it and here's the other pin\Nthat will let me connect my red lead.
Dialogue: 0,0:02:36.55,0:02:38.90,Default,,0000,0000,0000,,So I'm gonna connect\Nthose into the black and
Dialogue: 0,0:02:38.90,0:02:41.26,Default,,0000,0000,0000,,red rails on my circuit\Nright here like this.
Dialogue: 0,0:02:41.26,0:02:43.95,Default,,0000,0000,0000,,Okay, so I don't want to\Nmeasure resistance anymore now.
Dialogue: 0,0:02:43.95,0:02:45.06,Default,,0000,0000,0000,,Now, I want to measure voltage.
Dialogue: 0,0:02:45.06,0:02:46.42,Default,,0000,0000,0000,,So let's turn it over here.
Dialogue: 0,0:02:46.42,0:02:49.61,Default,,0000,0000,0000,,So I am measuring my\Nthree-volt source right there.
Dialogue: 0,0:02:49.61,0:02:51.74,Default,,0000,0000,0000,,That's 2.907 volts.
Dialogue: 0,0:02:51.74,0:02:53.84,Default,,0000,0000,0000,,Okay, let's probe my circuit.
Dialogue: 0,0:02:53.84,0:02:58.81,Default,,0000,0000,0000,,The first thing that I am going to do is\Nmeasure the voltage at each of my nodes.
Dialogue: 0,0:02:58.81,0:03:02.64,Default,,0000,0000,0000,,So right now, I'm measuring\Nthe voltage at the red node, see?
Dialogue: 0,0:03:02.64,0:03:07.33,Default,,0000,0000,0000,,This is the part right there connected\Non to the red node, it's right there.
Dialogue: 0,0:03:07.33,0:03:09.08,Default,,0000,0000,0000,,That's measuring three volts.
Dialogue: 0,0:03:09.08,0:03:11.81,Default,,0000,0000,0000,,Now, I'm going to measure\Nat the green node.
Dialogue: 0,0:03:11.81,0:03:14.79,Default,,0000,0000,0000,,Okay, at the green node,\Nso actually let me bit.
Dialogue: 0,0:03:14.79,0:03:21.81,Default,,0000,0000,0000,,Let me write right here that this was\N2.909 volts at the green node number.
Dialogue: 0,0:03:21.81,0:03:24.18,Default,,0000,0000,0000,,I said that was the green\Nnailed right there.
Dialogue: 0,0:03:24.18,0:03:28.85,Default,,0000,0000,0000,,At the grade node,\Nthis is two point six eight seven
Dialogue: 0,0:03:28.85,0:03:32.98,Default,,0000,0000,0000,,volts at the blue node\Nthere between the 3 and
Dialogue: 0,0:03:32.98,0:03:38.53,Default,,0000,0000,0000,,4k is 2.010 volts and\Nat the junction between the 4 and
Dialogue: 0,0:03:38.53,0:03:42.57,Default,,0000,0000,0000,,5k at the yellow node is 1.138 volts.
Dialogue: 0,0:03:42.57,0:03:46.52,Default,,0000,0000,0000,,Down here at the black node,\Nwe're back to zero.
Dialogue: 0,0:03:46.52,0:03:49.42,Default,,0000,0000,0000,,What I just did was that I\Nmeasured the node voltages.
Dialogue: 0,0:03:49.42,0:03:53.30,Default,,0000,0000,0000,,I measured the red node, the green node,
Dialogue: 0,0:03:53.30,0:03:58.09,Default,,0000,0000,0000,,the blue node, the yellow node and\Nthe black node.
Dialogue: 0,0:03:58.09,0:03:59.64,Default,,0000,0000,0000,,Those are node voltages.
Dialogue: 0,0:03:59.64,0:04:04.55,Default,,0000,0000,0000,,The way you measure a node voltage is you\Nplug the black lead of your volt meter
Dialogue: 0,0:04:04.55,0:04:05.78,Default,,0000,0000,0000,,into the ground and
Dialogue: 0,0:04:05.78,0:04:10.54,Default,,0000,0000,0000,,you move the red lead to touch each of\Nthe nodes that you are interested in.
Dialogue: 0,0:04:10.54,0:04:12.46,Default,,0000,0000,0000,,Now, let's measure voltage difference.
Dialogue: 0,0:04:12.46,0:04:16.99,Default,,0000,0000,0000,,The way you measure voltage difference\Nis you put your plug on one side of your
Dialogue: 0,0:04:16.99,0:04:18.48,Default,,0000,0000,0000,,resistor right there and
Dialogue: 0,0:04:18.48,0:04:21.89,Default,,0000,0000,0000,,you put your black plug on\Nthe other side of the resistor.
Dialogue: 0,0:04:21.89,0:04:25.82,Default,,0000,0000,0000,,This is now going to measure\Nthe voltage that's across R1.
Dialogue: 0,0:04:25.82,0:04:31.80,Default,,0000,0000,0000,,From red here to black there,\Nthat voltage is 0.223.
Dialogue: 0,0:04:31.80,0:04:34.95,Default,,0000,0000,0000,,We also can say that this is\Nthe plus side or the red side and
Dialogue: 0,0:04:34.95,0:04:37.32,Default,,0000,0000,0000,,this is the minus side, or the black side.
Dialogue: 0,0:04:37.32,0:04:39.54,Default,,0000,0000,0000,,Let's do the same thing for this resistor.
Dialogue: 0,0:04:39.54,0:04:41.58,Default,,0000,0000,0000,,Let's measure across R2.
Dialogue: 0,0:04:41.58,0:04:46.13,Default,,0000,0000,0000,,So let's put the black lead on\None side and the red lead on
Dialogue: 0,0:04:46.13,0:04:51.18,Default,,0000,0000,0000,,the other side just like that,\Nand that is 0.678 volts.
Dialogue: 0,0:04:51.18,0:04:54.68,Default,,0000,0000,0000,,Put a plus where your red lead is and\Na minus where your black lead is.
Dialogue: 0,0:04:54.68,0:04:55.72,Default,,0000,0000,0000,,Let's get this one.
Dialogue: 0,0:04:55.72,0:04:58.27,Default,,0000,0000,0000,,Make sure you fill out\Nthe cross our 4k now.
Dialogue: 0,0:04:58.27,0:05:06.85,Default,,0000,0000,0000,,That is 0.873 volts measuring from here to\Nhere plus on this side minus on that side.
Dialogue: 0,0:05:06.85,0:05:09.26,Default,,0000,0000,0000,,And now, let's measure across the 5k.
Dialogue: 0,0:05:09.26,0:05:14.80,Default,,0000,0000,0000,,Right there,\Nthis is 1.140 volts plus a new side minus
Dialogue: 0,0:05:14.80,0:05:21.23,Default,,0000,0000,0000,,on that plus it's always the red\Nlead minus is always the black lead.
Dialogue: 0,0:05:21.23,0:05:25.37,Default,,0000,0000,0000,,So what we measured there\Nwere the voltage differences.
Dialogue: 0,0:05:25.37,0:05:29.31,Default,,0000,0000,0000,,Now, let's take a look at\Nwhat we expect to happen.
Dialogue: 0,0:05:29.31,0:05:32.72,Default,,0000,0000,0000,,So we went from our\Napproximately 3 volts and
Dialogue: 0,0:05:32.72,0:05:38.04,Default,,0000,0000,0000,,we're going to have dropped 0.223\Nvolts down to our next node.
Dialogue: 0,0:05:38.04,0:05:38.93,Default,,0000,0000,0000,,Is that what happened?
Dialogue: 0,0:05:38.93,0:05:41.44,Default,,0000,0000,0000,,Take 2.9 subtract off 0.2.
Dialogue: 0,0:05:41.44,0:05:44.18,Default,,0000,0000,0000,,Yep, we've gotten down\Nto about this voltage,
Dialogue: 0,0:05:44.18,0:05:48.19,Default,,0000,0000,0000,,then we're going to have lost\Nanother 0.678 volts across our 2.
Dialogue: 0,0:05:48.19,0:05:49.98,Default,,0000,0000,0000,,In fact, subtract that off from here.
Dialogue: 0,0:05:49.98,0:05:52.34,Default,,0000,0000,0000,,Yep, you get down to the next node.
Dialogue: 0,0:05:52.34,0:05:55.50,Default,,0000,0000,0000,,Now subtract off the voltage\Ndifference here,
Dialogue: 0,0:05:55.50,0:06:00.25,Default,,0000,0000,0000,,0.87 and that is bringing you\Nto the 1.138 volts at this node.
Dialogue: 0,0:06:00.25,0:06:03.58,Default,,0000,0000,0000,,Let's also see how those\Nmeasurements could work this way.
Dialogue: 0,0:06:03.58,0:06:07.07,Default,,0000,0000,0000,,Let's measure the voltage\Nacross two of our resistors.
Dialogue: 0,0:06:07.07,0:06:10.44,Default,,0000,0000,0000,,So I'm measuring across R1 and across R2.
Dialogue: 0,0:06:10.44,0:06:12.48,Default,,0000,0000,0000,,What voltage do you expect there?
Dialogue: 0,0:06:12.48,0:06:17.36,Default,,0000,0000,0000,,You would expect to see the voltage drop\Nacross R1 and the voltage drop across R2.
Dialogue: 0,0:06:17.36,0:06:21.26,Default,,0000,0000,0000,,So this volt is difference\Nright there is 0.90 and
Dialogue: 0,0:06:21.26,0:06:25.36,Default,,0000,0000,0000,,that's plus were the red is,\Nminus where the black is.
Dialogue: 0,0:06:25.36,0:06:27.01,Default,,0000,0000,0000,,That's another voltage difference.
Dialogue: 0,0:06:27.01,0:06:30.01,Default,,0000,0000,0000,,What if I measured across\Nthree of my resistors?
Dialogue: 0,0:06:30.01,0:06:34.73,Default,,0000,0000,0000,,Add up the voltages that you originally\Nhad across the individually and
Dialogue: 0,0:06:34.73,0:06:39.14,Default,,0000,0000,0000,,that should give you the voltage\Nthat's across from R1 all the way
Dialogue: 0,0:06:39.14,0:06:44.12,Default,,0000,0000,0000,,over here to R3 plus on this side,\Nminus on that side, it's 1.775.
Dialogue: 0,0:06:44.12,0:06:46.18,Default,,0000,0000,0000,,Add those up, so\Nthat you can get the right number.
Dialogue: 0,0:06:46.18,0:06:49.57,Default,,0000,0000,0000,,And then finally, when I measure across\Nall of my resistors, sure thing.
Dialogue: 0,0:06:49.57,0:06:51.50,Default,,0000,0000,0000,,I'm back to my 2.9 volts.
Dialogue: 0,0:06:51.50,0:06:57.67,Default,,0000,0000,0000,,Now wait a minute, this says,\N2.915 when I started out with 2.909.
Dialogue: 0,0:06:57.67,0:07:02.57,Default,,0000,0000,0000,,Your voltages are not exactly accurate and\Nyour volt meters is not exactly accurate.
Dialogue: 0,0:07:02.57,0:07:07.00,Default,,0000,0000,0000,,So you can already see that I wouldn't be\Ntrusting these last two digits in this
Dialogue: 0,0:07:07.00,0:07:11.08,Default,,0000,0000,0000,,particular measurement between this\Nvolt meter and these voltages.
Dialogue: 0,0:07:11.08,0:07:17.100,Default,,0000,0000,0000,,So let's just focus on the first digit,\Nthe 2.9 which means let's get rid of this.
Dialogue: 0,0:07:17.100,0:07:19.57,Default,,0000,0000,0000,,Let's get rid of this.
Dialogue: 0,0:07:19.57,0:07:21.18,Default,,0000,0000,0000,,Let's get rid of this and so on.
Dialogue: 0,0:07:21.18,0:07:22.45,Default,,0000,0000,0000,,Those are your significant digits.
Dialogue: 0,0:07:22.45,0:07:24.79,Default,,0000,0000,0000,,So today, we have measured resistance.
Dialogue: 0,0:07:24.79,0:07:28.22,Default,,0000,0000,0000,,We've measured node voltage and\Nwe've measured voltage difference.