How Resistors Work - Unravel the Mysteries of How Resistors Work!

why do resistors burst into flames why are there so many different types what do these stripes mean and how do resistors even work I'm going to tell you in this video you can even buy a mug or a hoodie to support the channel links down below for that along with links to our sponsor PCB way who offer everything from circuit boards 3D printing CNC Machining injection molding and even sheet metal fabrication do check them out links down below resistors look something like this they come in many shapes and sizes they are represented with symbols like these in engineering drawings if we take this LED and connect it to a 9 volt battery it will instantly be destroyed inside the LED is a thin wire and the battery will try to push so many electrons through this wire that it breaks so we use a resistor to reduce this current of electrons the resistor is removing energy from the circuit to protect the LED it is literally turning the electrical energy into heat in order to remove it resistors make it harder for electrons to flow so they add resistance to a circuit resistance is a measurement of how easily electrons can flow through a material and we measure this in the unit of ohms many people incorrectly think that the resistor acts like a speed bump only slowing the electrons down momentarily but they act more like a traffic jam restricting how many electrons can flow the speed of the electrons Remains the Same think of water flowing through a pipe it's easy for it to flow but if we partially block the pipe we add resistance to the pipe the water collides with the pipe and so it's harder for the water to flow and we also have a pressure drop across the Restriction the same with electricity electrons can easily flow through a wire but if we add a resistor then the electrons will collide so it's harder to flow and so the current is limited we also have a voltage drop across the resistor these collisions convert the kinetic energy into heat and that's why the resistors become hot most of you will recognize these types of resistors the metal film resistor carbon film resistor or the carbon composite resistor I'll explain how these work later in the video and you can even try to make some circuits yourself these are all through hole type which we can plug into prototype boards or we can solder into printed circuit boards circuit boards typically label the components so that we can identify their position we can buy resistors in bulk very cheaply which is perfect for learning electronics and making mistakes I'll leave a link down below for where you can buy them these have a fixed resistance and on the side of the resistor we have these colored Stripes which indicate the resistance value I'll show you how to read that later in the video we also find SMD or surface mount device type which I use for compact circuit boards these are soldered directly onto the metal pads on a circuit board we can use a soldering iron or solder paste but some are so small they require a specialist machine these have a fixed resistance and on the top is a number which indicates the resistance value I'll show you how to read that later in the video all of these resistors have a fixed resistance value but we can also get variable resistant types too we find manually adjustable versions like potentiometers and rheostats which we can adjust using the dial some are very small and are used for the calibration of circuits then we have automatic versions like thermistors light dependent resistors viristers Etc all of these resistors will have a rated maximum resistance voltage and power the resistors will generate heat and at a certain point they won't be able to dissipate sufficient heat the temperature increases so much that the protective layout catches fire and the resistor is then destroyed but I have a question for you should a resistor be placed before or after this led tell me in the comments section and I'll give you the answer at the end of the video let's look at how the different resistors work and their Construction carbon composite resistors are made by mixing a conducting material such as carbon or graphite with an insulating powder such as clay this forms a solid core and we then Place metal connectors at each end this is enclosed within an insulating case the electrons flow through the solid core if we look inside one we can see that there is a solid core with the metal connectors at each end and then the insulating case now these type are not commonly used anymore just because modern resistors have better performance stability and they also last much longer carbon film resistors are very common and they're also very cheap to produce they consist of a ceramic core which is coated in a thin layer of carbon the metal connectors are attached with end caps and this is all covered with an insulating case to control the resistance value a helical Groove is then cut into the layer of carbon this creates a narrow path for the electrons and by changing the pitch of the helical cut we can increase the length of the path and also reduce the width of the path and so the resistance increases looking at these examples we can clearly see the one ohm resistor has a short Groove and a wide path the one kilo ohm has almost three rotations and the path is much thinner and then the one Mega Ohm resistor has almost five rotations with the path being very thin so resistance is very high these are available in different sizes the larger the resistor the more heat it can dissipate because of the larger surface area so the bigger the resistor the larger the power rating we usually find four stripes on these resistors which indicates the resistance value the packaging usually tells us the resistance or we can quickly measure it with a multimeter however sometimes we need to look up the values using this chart we have two digits a multiplier and a tolerance band the tolerance band is separated from the other stripes we start with stripe one which is brown so this is one the second stripe is black which is zero the third stripe is the multiplier which is brown so this is 10. therefore one and zero are 10 multiplied by ten gives us 100 ohms and the final stripe is the tolerance this one is gold and so it's plus or minus five percent meaning it could be as low as 95 ohms or as high as 105 ohms when I measure this one with a multimeter we can see it is reading 98.2 ohms okay can you work out the resistance of this one by yourself tell me in the comment section and I'll give you the answer at the end of this video metal film resistors are very common they consist of a ceramic core which is coated in a thin layer of metal the electrical connectors are attached with end caps and this is all covered with a protective coating the metal layer has a helical groove cut into it to increase the resistance this increases the length of the path and also reduces the thickness which makes it harder for electrons to flow through without colliding and so the resistance increases we can see this 10 Ohm resistor has a very wide and short path so the resistance is low if we compare it to this one Mega Ohm resistor which has a very thin and long path so the resistance is very high this type of resistor has a high tolerance and a very good stability so it is often preferred over the carbon film or the carbon composite although it is slightly more expensive they are available in different power ratings the larger the size the higher the rating and the more heat it can dissipate the colored Stripes indicate the resistance value and we usually have five stripes on these type the packaging normally tells us the resistance or we can check with a multimeter otherwise we can use this chart to look up the values we have three digits a multiplier and a tolerance band the first stripe is orange which is three the second stripe is orange which is three the third stripe is black which is zero combine these numbers to get 330. the fourth stripe is the multiplier which is black and this is one so 330 multiplied by one is just 330 ohms the fifth stripe is the tolerance this is brown which means it's plus or minus one percent so it could be between 327 and 333 ohms when I measure this one it's 329.9 ohms so can you work out the resistance of this one by yourself tell me your answer in the comments section and I'll give you the answer towards the end of the video wire wound resistors come in different designs they offer very high power and current ratings you can see they are very basic just a wire wrapped around a ceramic core and are then covered with a thin layer of insulation the thickness length and material used dictates the resistance this one shows it's rated for 50 watts and 2 ohms some are buried in a ceramic block with cement but inside these there is just a coil of resistive nechrome wire wrapped around a ceramic core with two end caps attached these are used in high heat applications as the cement and ceramic layer protect the internal wire this one shows it is rated for 10 watts and 10 ohms another common example is this design which uses an aluminum casing that helps dissipate lots of heat these ridges increase the surface area so more unwanted heat can leave the resistor there are holes in the casing so that we can mount this to a surface inside we find a ceramic core with a coil of resistive nechrome wire between two electrical connectors this typically has some form of insulation around it and then it is enclosed within the metal housing with some resin end caps this one shows it is rated for 10 watts and 33 ohms surface mount device resistors are available in many sizes some like this one are so small you need a microscope to see them the construction is quite simple they typically have a ceramic body with an electrode on each end these are connected by a thin layer of resistive material and then covered with an insulating protective case and capped off with metal connectors the resistive material has a groove cut into it with a laser this reduces the area in which electrons can flow and so the resistance increases these provide high tolerance but they have a very low power rating on the top are some numbers this indicates the resistance value we have a three digit version the first two digits represent the significant values and the third digit is the multiplier or how many zeros are after the significant value for example this one shows two four zero the first two digits are 24 and we multiply this by one so this is just a 24 Ohm resistor this one is one zero one so it is 10 multiplied by ten making 100 ohms this one shows one eight three so it's 18 multiplied by 1000 or 18 kilo ohms with four digit codes the first three digits represent the significant values and the final value is the multiplier this one shows one zero zero zero so it is 100 multiplied by one meaning it is a 100 ohm resistor this one shows three five zero two so this is a 35 kilo Ohm resistor sometimes we have the letter R before or between the values we treat this as a decimal place so this R56 resistor is 0.56 ohms this 47 R5 resistor is 47.5 ohms we also find three digit value versions with letters at the end we have to look up these values on a table we start by finding the first two values on the chart in this case 26 which is 182 and then we find the letter which is C and that means multiply it by 100 so this resistor is eighteen thousand two hundred ohms this one shows 60 Z and so we look up 60 which equals 412 and Z means multiply by 0.001 and so that gives us 0.412 ohms potentiometers have a dial which lets us change the resistance we have General use versions which we might use for example on volume control and then we have Precision ones which are used for tuning electronic circuits we can see they have three terminals inside we see there is a resistive track which runs between the two end pins and then a dial attaches from the track to the center pin moving the dial increases the distance the electrons have to flow so the resistance increases we can connect it in the opposite way also like any resistor we will have a voltage drop across the two end pins because of the resistive track so by connecting to the center pin we can just use part of this resistive track so we only have part of the voltage drop this allows us to control the output voltage from this pin additionally we can use just the center pin and one end pin to create a rear step the total voltage drop now occurs between these two points and so we can control the current in the circuit like this on the front of these components we find a number this indicates the maximum resistance this one shows 1K so it's 1 000 ohms this one shows 500k so it's 500 000 ohms the letter indicates the type B is very common and it means the resistance changes in a linear way but we can get logarithmic types too these small versions have a three digit number the first two are the significant numbers and the third tells us how many zeros to add for example this one shows 1 0 1 meaning it's ten with one zero after so is a 100 ohm resistor and that is the maximum rating this one shows two zero four so it is 200 000 ohms Rio stats are used to control current in a circuit the current is typically large hence the size of the component these are connected in series with the load we only use two terminals at a time even when three or maybe four might be available smaller current circuits can use a potentiometer as a rear step the riostat uses a resistive wire which is coiled around an insulating ceramic core this core is typically an arc shape or it might be cylindrical the further the arm moves along the wire the further the electrons will have to travel through the wire and so the higher the resistance will be we can see this one uses a raised surface on the sliding arm to make the connection to the coil and this one uses a replaceable carbon brush with a flexible connection to the center terminal on the side of the component we usually find the maximum resistance maximum current or maximum power rating fusible resistors look similar to a standard fixed value resistor but when we overload a standard resistor it will burst into flames however when we overload a fusible resistor it heats up and then it just breaks the circuit without bursting into flames so it's a resistor but it will act as a fuse to protect the circuit inside this we typically find a ceramic core with a resistive wire that spirals between the two end caps this is then covered with a protective fire resistant resin layer the wire acts like a fuse wire and heats up but at a certain temperature it will snap which then cuts the circuit other versions use a thin layer of metal alloy instead of a wire and the groove is then cut into this layer to control the power for the current can flow we can see that this one has five bands the last one is white which indicates that this is a fusible resistor the other four bands indicate the resistance we can look up the values using this chart we see the first value is yellow which is four the second band is violet which is seven the third band is black which is one so 47 multiplied by one is 47 ohms and the fourth band is gold which is plus or minus five percent so it is rated for 47 ohms but it could be anywhere from 44.65 to 49.35 ohms Baristas are variable resistors although we can't control them like a potentiometer instead they automatically control their own resistance depending on the voltage in which they are exposed to it looks very similar to a ceramic capacitor but it acts slightly like a schottkey diode we typically connect it in parallel across the supply for a delicate electrical circuit ordinarily it might have a very high resistance so it acts like an insulator and almost no current will flow through it but at a certain bow voltage it will become a conductor and short to ground this is very useful as it protects the circuit against voltage spikes inside we typically have a mixture of zinc metal oxide grains with a ceramic core this is capped with metal plates and electrical connectors and then it is covered with an epoxy protective casing we can see this one has some digits on the front the 14 indicates the diameter the D indicates the shape then we have one two one this means 12 with 1 0 after so it is rated for 120 volts the K indicates a tolerance of plus or minus 10 so it could be anywhere between 108 to 132 volts thermistors are thermal resistors we have the NTC and the PTC types NTC will decrease in resistance as the temperature increases PTC will increase in resistance as the temperature increases we can get them in film ceramic bead chip disc and glass encapsulated forms their construction is quite simple just a layer of semiconductor between two conductors and this is covered with a protective coating the semiconductor material acts as an insulator so the atoms hold on tightly to the electrons but as heat is applied the thermal energy excites electrons giving them enough energy to break free from the atoms so a current can then flow more heat means that more electrons can flow and so the resistance decreases these are very useful for inrush current limiting temperature sensing temperature control and the glass ones are very good for high temperature applications resistance temperature detectors are a simple temperature sensor they typically consist of a ceramic core of a plasma wire wrapped around it and connected between two electrical connectors and this is then covered with a protective coating they are often fitted inside a metal case to measure liquid temperature Platinum is used because its resistance increases in a near linear pattern as temperature increases so this makes calculations very easy when the wire is heated the resistance increases that's because the atoms inside become excited and move around this makes it harder for electrons to pass through without colliding so the resistance increases as temperature increases light dependent resistors are variable resistors they will automatically adjust their own resistance depending on how much light they are exposed to they have a ceramic base which is coated with cadmium sulfide this is then covered with two electrode plates separated by a small Gap electrical terminals connect to this and we usually find a clear protective coating covering the component ordinarily they have a high resistance electrons within the cadmium are held in place by their atoms but when exposed to light the photons will pass through the Gap they will then hit the atoms of the cadmium and knock some of the electrons off another electron will then move to take its place as the light increases more electrons start to flow so the resistance decreases as light increases they come in a range of resistance values but they don't typically have any markings on them we only find this on the packaging to identify them you have to test them in complete darkness these are useful for automatic night lights and dark sensor circuits strain gauges look something like this it's a sensor which deforms under stress we can see there is a layer of insulation and a thin conductive layer of foil looping in a grid pattern which provides a path for electricity when at rest we can see that the strain gauge has a certain resistance but if we deform it this way the resistance increases and then if we deform it this way it decreases that's because the material is stretching and Contracting so the length and the width of the conductor is changing in very small amounts longer thinner wires have more resistance than shorter thicker ones these are often used in wheatstone Bridge circuits to measure pressure like in an electronic pressure switch don't forget to check out PCB way for all your 3D printing CNC Machining injection molding and even sheet metal fabrication needs I have a link for you in the video description down below take a 9 volt battery and using a test board insert a one kilo Ohm resistor and then connect the battery electrons are flowing from the battery and through the resistor we should see a current of around 0.009 amps we can calculate it like this this gives us a power dissipation of 0.081 Watts as this is a 0.5 watt resistor it will work fine and generate a little heat but if we connect a 10 Ohm resistor it will catch fire that's because the current is now around 0.9 amps and so the power is around 8 watts this is only rated for 0.5 Watts so it rapidly overheats and catches fire so we can see that the higher the resistance the lower the current will be if we connect a red LED we have a 470 Ohm resistor to the 9 volt battery the LED shines brightly it doesn't matter if we place the resistor before or after the LED it will be the same the current is around 0.015 amps the LED is dropping roughly 2 volts and the resistor is dropping a further 7 volts the power dissipation is around 0.1 Watts if we use a 10 kilo ohm resistor the LED is very dim the current is around 0.0007 amps but we still have a voltage drop of two volts on the LED and 7 volts on the resistor the resistor is just limiting how many electrons can flow if we connect the LED with a 470 Ohm resistor and then connect them to the center pin of a one kilo ohm potentiometer we can now dim the LED this is acting as a rheostat limiting the current with the dial all the way to the left the LED is at its brightest and there is almost no voltage drop over the potentiometer the resistor has around 7 volts and the LED has roughly 2 volts the current is around 0.015 amps with the dial all the way to the right the LED is at its dimmest the current is around 0.005 amps we have a voltage drop of 1.9 volts on the LED 2.2 volts over the resistor and 4.9 volts over the potentiometer so we can vary the resistance to control the current in the circuit we know that there is a voltage drop over a resistor if we have two equal size resistors in series the voltage drop will be the same across each so if we measure between the resistor and ground we can access half of the voltage and we have therefore created a voltage divider the same current flows through both of them but the voltage drop and power dissipation is different it has been divided if we swap the first resistor for a 470 Ohm resistor we have access to 6.1 volts if we swap these over we then only have access to 2.9 volts so we can control the output voltage by controlling the resistor values or we could use a potentiometer the dial lets us use just part of the resistor so we have just part of the voltage drop we can also make a current divider by placing resistors in parallel a single 470 Ohm resistor will cause 0.019 amps to flow if we added a second in parallel it would also pass 0.019 amps the paths then combine and so the total current would be around 0.038 amps we could either use one 235 Ohm resistor or two 470 ohm resistors in parallel the total current and power is the same but in parallel the current and power is shared okay so to answer the questions the resistor can be placed before or after the LED it will not make any difference the carbon film resistor has a rating of one Mega ohm and the metal film resistor has a rating of 22 kilo ohms check out one of the videos to continue learning electronics engineering and I'll catch you there for the next lesson don't forget to to follow us on Facebook Twitter LinkedIn Instagram and the engineeringmindset.com

Channel: The Engineering Mindset

Views: 1,396,912

Keywords: how resistors work, how do resistors work, what is a resistor, resistors, resistors explained, electrical engineering, electronics engineering, how resistors work animation, resistors in series, basic electronics, what is a resistance, how does resistor work, potentiometer, current division, current divider, power electronics, city and guilds, current limiting, variable resistor, voltage drop, resistors and resistance, circuit theory, ohms law, all about electronics, resistor

Id: DYcLFHgVCn0

Length: 28min 22sec (1702 seconds)

Published: Sun Mar 12 2023

Reddit Comments

[u/LoraxEleven]

Fucking excellent. Takes me way back in time. Also a pretty cool channel altogether. Thanks for putting it up.