LED resistor value calculation explained (Ohm's Law)
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- čas přidán 17. 11. 2015
- Using Ohm's law Kevin explains why we always use a series resistor, and explains how to calculate the value of the resistor.
Once you understand the Ohm's Law triangle making these calculations yourself is simple and straightforward.
For more information and to use our handy calculator visit www.kitronik.co.uk/blog/led-r... - Věda a technologie
You should push all of those Universities out of the way and get paid all of the money they are stealing, I spent 4 years in college trying to understand this and in 3 minutes I fully understand. Great Job! I'm going to subscribe to your channel
Thanks for the subscription, and we're pleased our video helped out!
i spent hours online, come to your video. now im asking myself how i didnt understand hours ago. thank you so much cleared things right up
👍 😊
What happen if I attache this led to 230v ac directly with a resistance in series then ... If the same formula will work ??
@@vedurj9723 You will need to source LEDs that have been designed work with an AC supply at that voltage.
Nice name dude
The explanation I was looking for, and very easy to understand. Thank you!
Super clear and concise, thank you for the explanation!
That was very clear, it helped me a lot . Thanks
Thank you for this clear & concise video.
👍
U R Super
You make it so simple that any body can understand.
*Simple
*Clear
*Short, and you also have a good hand writing.
Congratulations 👌
Hey I wanted to personally thank you, I have had trouble getting the premise of ohms law. But you were able to cement it for me, Thank you.
Thanks for the feedback, we are glad it helped you!
Very clear explanation. Thank You!
Thnk you sir because of you now I am able to understand the basic of finding value of resistors 👍👍👍👍👍👏👏👏👏👏👌👌👌👌👌
HHH Great work amigo, very clear and loud,
Thanks for the explanation!
NICE AND EASY WAY TO LEARN THANK YOU
Very nice precise video. Move camera to your left side so we see you writing as you
explain 👍
Great video thanks, if you would have also explained the resistor wattage, the video would be complete. 👍
Thanks for the explanation :)
Nice explanation detailed by detailed. .thanks. .
thank you for the explanation
Thank you for the explain
Thank you so much for this simple equation. And then there was light :D. Just a simple question. When i want to power 2 LED lights in the example circuit in the video will i add a 660 resistor or 150?
good explanation thanks
Thank you so much.........
Really super bro
wow clear explanation
Hi I've bought some small smd's 3.4v and 20ma max I know for 1 led I need 300 resistor but I need to put 8 of these leds together for my project so what resistor would I need and how would I work it out. Thanks
Nice tutorial. Is there any table list that gives the current values that going through LED's?
Manufacturers or retailers should be able to provide this info. We list all of ours on our LED listings.
Thank you
thank you very very very much my deer
that calculator is awesome ..... :D
Thank you!
Thank you!
How can I calculate the resistor if the input is 220v using the 3v LED. Thanks
nice one thanks
I am running out of patience waiting to see who will have the brilliance to make a video explaining how to calculate the current limiting resistor for an LED with UNKNOWN specs.
Hi, personally I wouldn't use an LED that I didn't have the specs for. I would order a replacement and go from there.
How do you calculate the resistor value of a 34V and 600mA current LED Chip running off of a 12V power source???
now i know!!! thank u
What about the watts? Do the resistor watts is based/same on lights power/watt?
So if I have 19 volt power supply and my LED is rated 12 volts, do I have to get abaot 400 ohm resistor? Anyway I don't know the current that flwos true the resistor or the LED.
If I want to create a custom strand of 1.8mm LEDs with let's say 50 LEDs in the strand do I put one resistor at the beginning or one at each LED?
If they're in series then you just need one at the beginning.
i have SMD led white 4.5mm ( 3w ) wide angle, not sure what is mA.
Anyway i put a 470ohm 1/4w resistor and its dimming every each led no metter what type of led but if i put 3x470ohm then every time i put extra resistor its getting brighter. im connecting 12v supply
Im ok that is diming but i think it might be dimming to much , as far im aware it just should allow led to work under 12v pressure and keep normal brightnes, but its dimming a lots.
What im doing wrong?
hi,
sir can you help me! i want make led lights for my car so i don't know about ohm law can you help with the figure i want to buy the exact one the value which written on the ebay it's like this (47k) so which one is good for 12 volts?
bro nice video i like it
but this is for only 1 led
can you plz explain me how to calculate resistance of 2 led with same volt (connected in series or parallel )
You can use this handy calculator to work it out for you. www.kitronik.co.uk/blog/led-resistor-value-calculator
What happens if instead of the 9 volts DC we switch to 120V AC? is that possible? Thanks ! Subscribed!!
You risk serious injury.
I have a bunch of LEDs laying around and I don't know where they're from. How can I figure out what resistors to use? Is there some way to measure it?
How would the resistor vary if I were to put a series of those led diode? Say 10? Is it necessary to use a different value resistor?
Yes. You can use this handy calculator here www.kitronik.co.uk/blog/led-resistor-value-calculator and adjust the amount of LEDs.
From where u got the amps of the led??? What if we choose a random led and what if we dont have that machine? In that case what should we do?
The power requirements can be found on the datasheet for the LED.
If you use different components you can work out the value of the resistor by changing the ohms law calculation to match your scenario. I hope this helps.
Yeah... but what if you have no idea of what the forward voltage of the LED is, and no way to access its datasheet because you salvaged it from electronic scraps, or you bought it in bulk from an obscure source?
hello sir
question please:
i want to connect 5 led's together to make a led bar. each led is 12v
and 10w. what resistor should i use?
thank you sir.
It depends on the power supply, but 50W is quite a lot.
Have you considered these instead?
www.kitronik.co.uk/35129-zip-strip.html
What is the calculation if you have 10 LEDs wired in parallel, is it a simple times 10 of the 20ma ?
Also to get the correct resistance, why not put two resistors in parallel or series ?
Hi, we have a resource that details how to do calculations for series and parallel configurations, it should have the information you require. I hope this helps.
kitronik.co.uk/blogs/resources/how-to-calculate-resistors-in-series-and-parallel
Howdy, Brother! What resistor should I use if I have a yellow 10mm LED Emitting Diode (1.8-2.2V) powered by two AA Batteries? I will have an on/off switch in the loop. Will 47 ohms work? i tried 100 ohm resistor but the batteries were getting hot. I'm not even sure if I asked the question properly . Thanks for any assistance.
Hi, and thanks for the question. If it's a standard LED then 47 ohms should be perfect for the job.
We have a pretty cool calculator on our website that can be used for this. Select the LED you have from the dropdown list and then use the button to pull through the details. Add your supply voltage and then hit the calculate button. I hope this helps;
kitronik.co.uk/blogs/resources/led-resistor-value-calculator
@@kitronik Thank you, Brother! By the way, your LED Resistor Value Calculator is fantastic. Nice work!!
Please sir 8mm blue led 3bulb...what resistor use 12v
damn.. now I get it...
Nice video, but the resistor is useless if you use a 3 volt battery or 3 leds in series ?
Hi, the video is a practical example of how to use ohms law to determine values you don't know using values that you do know. If your 'known' values are different you can still use ohms law to determine what you don't know. The numbers may be different but the process remains the same.
what if i have a 3mm led @1.8v 20ma forward current
what value of resistor do i need to prevent it from dying haha
example my power input is 5v with 2amperes of power
then i'll make 42led in parallel now the forward current will become 840ma
I have an LED bulb which is 12v 35w, so 2.9a, but my power supply is also 12v. How do I calculate that? Cheers!
What resistor do i need for my led if i want 3 volt but my battery is 5 volts please answer
Sorry still not understanding. If the power going to my 3v led is 12v 5a, what resistor should I use? Please help. Thank you
If you have a 12V power supply and the voltage drop is 3V for the resistor, the top part of the triangle (Value for V) would be 9. The amps of the resistor in our example is 0.02A but in yours would be 5A. So 9 divided by 5 = resistance.
If I have a 12v 30amp power supply I need to power 5 modules which take up 12 V and 1.2 Amps each what do I do I’m afraid I will blow up the modules
What if you have led’s with no data available? I have tons of them. Do you just assume that they are rated at 20 ma? They are different dimensionally, and color.
Hi, thanks for your question.
In the absence of a Datasheet, there are a couple of things you can do;
It is possible to find out an LEDs forward voltage with the test diode function, which can be found on some multimeters.
You can also hook up the LED to a potentiometer/variable resistor and a battery. Have the potentiometer set to its highest resistance value. Slowly decrease the amount of resistance, until the LED is lit fully, being careful to not go too far so as to damage the LED. You can then use a multimeter to check voltage and current.
When sorting through your LEDs and deciding which to use, we would advise you to stick to an LED current in the range of 10mA to 20mA.
I'm still confuse ..
How did you find the amp??
Can i find it with the resistor connected in serries to the led?
Because if directly connect it to battery the led will blow ..
You can calculate it using ohm's law;
czcams.com/video/GP-KWqKvv9I/video.html
how can I calculate the internal resistance of a LED if I do not have datasheet and how to calculate threshold voltage of LED ?
to calculate INTERNAL RESISTANCE
Use a Multimeter in Resistance Mode
that should have been obvious
As for forward voltage
Use a Multimeter.... DIODE MODE
the reading you get will tell you the min required voltage needed for it to conduct
or.... Use a Power Supply... Very low CONSTANT VOLTAGE start in mV range
and slowly go up until it starts to conduct
your Power supply will then tell you both the voltage and current that you require
If i use 5 small led, the power source is 12V with max 2A current, then what is value and no. of resistor taken so that the bulbs not get fused ?
Hi, if the LEDs are in series only one resistor is needed for the circuit. If the LEDs are to be in parallel then each LED would typically have its own resistor. If the LEDs are identical then the resistors would all be the same.
Without more information about the LEDs, current requirements and forward/drop voltage, we can't do any calculations.
I hope this helps.
If I connect more led (for example 5 ) then how many resistor needed..?? Is the one led enough..??
You can use this handy calculator to work it out for you. www.kitronik.co.uk/blog/led-resistor-value-calculator
What if we have a 3V power supply and a 3V bulb?
hahahahah I like the ads "MAERSK" I really thought it was a movie
Can some one help me I'm really new to this... so example if I used everything within his video ie the battery the resister and the led values ... what if I add more than 1 led then what happens do I need another resister or do I only need 1 for multiple leds attached in a line ??? Little co fussed lol
Assuming the LEDs are in parallel then you add both milliamp values together before doing the calculation, and just use one resistor. Play with the values on our calculator to see how it changes: www.kitronik.co.uk/blog/led-resistor-value-calculator/
How to know LED voltage or current?
If 30 leds of 3.9v are connected in series for 12v Dc then how much resister should be used? ?
It depends also on the forward current of the LEDs.
Nice video, but what if the power supply gives 12 V and 90 A (PC PSU). What happens then? Is the same? Just apply Ohm's law and forget about the current given by the PSU?
Hi, if you refer to the datasheet for an led you will find information regarding the max forward current. Always use a power supply that is appropriate to avoid damaging your circuit/self. I hope this helps.
@@kitronik As long as it meets more than the current required. So Just about any D.C. source can be used, Batteries or Power Supply . The current is so minimum, no worries!
As long as you adjust the voltage down to requirements of the circuit. Or add a resistor in series with the supply.
how will you measure the current if you dont know yet the value of the resistor needed?
You use the current you want to flow through the resistor, taken from the datasheet.
Which resistor should I use for 40W led
1 ohm 1/4 watt @ 440v
Hello,
i tried calculator but i still have a question.. About wattage.
My motorcycle gauge cluster bulbs are halogen 12V 2x 0.7w and 1x 1.1w. If i install T3 leds 12V 0.2W 20mA.... what resistors do i need?
In calculator i found 600 Ohm, but in market i findf 600ohm resistor 2w. Wattage affecting? I wouldnt like to cause any damage.
I look forward to hearing from you,
Thank you.
Hi, a wattage value indicates the maximum amount of power that the resistor is rated for. Most circuit diagrams will not show any power ratings for resistors as the power involved is low. You would need to see the actual circuit diagram for the cluster on your bike. If the circuit diagram indicates resistors with a specific wattage rating then you should definitely follow that instruction.
You can calculate power with watt's law; Power (in Watts) = Voltage (in Volts) x Current (in Amps)
I hope this helps.
@@kitronik Thank you for your reply, i really appreciate it!
Bro...If we connect 25 LED light (8mm) in series, what is the resistance (value) we must use in the circuit designed??
What is the Voltage of the LED's ??
What is the Voltage of your supply ?
How much current is being supplied ?
as for the Voltages and resistances
When you contain Voltage IN SERIES it's additive , Meaning if you have a 1.5V Battery and you series it with a 1.5 V Battery
You're going to have 3V DC for obvious reasons
so.... let's say each of your resistors needs 2V and you have 25 of them
well, then you have to factor in 50V DC in your calculation
so let's say you have a 120V DC Source
then you need to figure out the current
let's say 500mA for arguments sake
and let's say
so to solve for Resistance you have
R = V \ I
so.....
Voltage = 120 - 50 = 70 V DC
Current = 0.500A
therefore
70 \ 0.5 = 140 Ohm RESISTOR is needed
Does that makesense ?
@@martinkuliza 3.2-3.4v
Power supply=230v
@@feminsimon6189
you still failed to answer 2 Questions that i asked
1. how much current is being supplied
2. Does that make sense ?
i can't answer your question until you answer those questions
1:55 "the voltage across the resistor is 6V, this is because it is 9V from the battery less the 3V that's dropped across the LED"
I don't understand, does the LED _absorb_ those 3 volts? I've never heard of anything like that before. And then, how does the resistor know about something that happens after it in the circuit? I assume the electron stream coming from the anode could tell something about the voltage being pulled, but it still doesn't make complete sense to me.
Could you illuminate this?
Hi.
The LED doesn't so much absorb those 3V as convert them to light.
To explain properly we need to take into account a couple of other relevant laws of Circuit Theory - Kirchhoff's 1st and 2nd Laws.
Kirchhoff’s 2nd law states that the sum of voltages around a closed circuit is equal to zero.
We can use this to determine the resistance required to limit the current to 20mA
We have a 9V battery, and we want to have 3V across the LED. Using Kirchhoff’s 2nd law: 9V -3V -(voltage across Resistor) = 0
So we need to account for 6V of energy for the resistor. (We convert it from electrical energy to heat energy, for circuit purposes the important bit is that it's no longer electrical energy.)
Ohms law states that the voltage across a resistor is related to the current through it by its resistance (V = IR)
Kirchhoff’s 1st law states that the currents flowing out of a node are equal to the currents flowing into the node - in other words in our simple single loop circuit the current is the same at all points.
Because we now know that there must be 6V across the resistor we can work out what the resistance needs to be to limit the current to 20mA.
This is 6V/20mA = 3000 ohms.
Hope this helps.
Thanks! That is a great explanation!
Please give me the datasheet of The current of the LED
what if used a 12volt car battery, is it the same, because it has alot of power?
Check the datasheet for the LED you have, that will tell you what sort of power requirements the LED needs.
Can you please tell me how much ohm resistor can use with 22leds in parallel and flowing current is 12v battery
You also need to know the forward voltage of the LED (the amount of volts the LED needs to light up).
ok thanks can you explain me more about this
LEDs need an amount of voltage to light up. This depends on the LED. It might be 2.1V or 3V for example.
The difference between the voltage supply, and the amount the LEDs need is the amount you need to provide resistance for.
For example if you have two LEDs that need 3V each and you have a 12V supply, you need to calculate the resistor for 12V - 3V - 3V = 6V.
thanks
hi i wanna tell you something i am working on a small project to "AJ" sign with led's i am using 22 leds of 2v to complete and power supply 12v 's 4 ampere bike battery actually this AJ is for bike and also finished this yesterday using 230 ohm resistor can u tell is it right or not
Ajay, if you have 22 LEDs rated at 2V each then a 12V power supply will not light them at full power.
I had a memory hole, tanks
what about if my battery has 2v and i need 2v then there is 0v going to the resistor how do i calculate that?0v/0,02a is zero so should use no any resistor or what. i didnt use any resistor and my led got burnt..any ideas? I am very new in this please can someone explain????
Hi Simon. If the battery and LED are both 2V then you shouldn't need a resistor. Use a multimeter to double check your battery output.
Does it matter if the resistor is on the positive or negative side of the LED?
Sizzlik should be on negative i think
So long as you add the resistor in series it doesn't matter.
It does not matter. Because the current (ampers) is the same everywhere.) But it will be more correct to connect it before the LED, on anode, positive side, longest leg.
With respect: It will not be "more correct" to connect it on either side. It literally doesn't make any difference.
How to check led value?
what if i had a 3v led and a 3v battery. will the battery give out too much current or does the battery only supply the max 20mA the led requires? Will this battery safely light the led for long periods of time. Want to make a simple touch switch circuit activated by water to last 8 hrs if possible.Thanks. Great video.
It is common to use a 3V coin cell directly on a 3V LED (take a look at throwies) but it does depend on the capacity of the battery. To be sure you can test with a multimeter.
This was 90% there for being my cure-all answer. I wish that you would mention what term (similar to "Forward Voltage") to look for to find the mA on the LED datasheet. This seemed like a big detail, mainly because so much of starting out is understanding how to make sense of those over-packed data sheets haha.. I believe that term is "Continuous Forward Current" but correct me if I'm wrong.
This other video helped me understand ohm's law in a bit more long-winded way... a combination of the two was the perfect solution. czcams.com/video/fGI9d0CjI8s/video.html
Correct, you are looking for the Continous Forward Current, but it is often also listed as Typical Led Current.
how we can calculate I=?
I = V/R
I want to put some leds on my car i have subtracted 3 out of 12 then divided 9 by 0.02 it gave me 450 so that means i have to buy 450 ohms resistor?? Please help
You need to find the forward voltage of the LEDs you want to use and use that value in the calculation.
Kitronik what do you mean by forward voltage bro? I have a 3v led and its 760mA and i want to run it by 12v how can calculate this?
The forward voltage is the 3V bit.
So 12-3 = 9V.
Divided by 0.76A (760mA = 0.76A) (This is because our LED was 0.02A but yours is 0.76A).
Kitronik okay bro I've took 9/0.76 it gave me the result 11.842 now this is lil bit confusing how do i know how many ohms is 11.842? Is it 1k ohms??
It's exactly that, 11.842 Ohms. Nearest resistor you can get is probably 15 Ohms.
how do i work out the MA?
The current will be on the LED datasheet. Alternatively if you know the Voltage and Resistance you can use the triangle to work out the milllamps of an LED on a given circuit. Voltage divided by resistance equals current.
thank you for your response. As a motor mechanic i should know this. I learned it at collage 4 years ago. Its the first time I have actually needed to use a resistor in the field. fuses all the time. its easy to put a new "resistor" or "fuse" in from a spread sheet but its nice to actually going on
FYI .... MA means Mega Amps
mA means milli Amps
9v battery requires how much ohm resistance to light 5v singe led
It depends on the current needed by the LED.
5v DC current
Current is measured in Amps. You need the current figure to do the calculation.
@@IMRANMOBILEWALA
hehe
there is no such thing as 5V DC Current
there is such thing as 5 VOLTS DC Meaning......
Step 1. Buy yourself and Oscilloscope
Step 2.Attach a DC Power supply to your scope that Is set to precisely 5V
you will notice that your scope shows you a straight line (Assuming your calibrated your marker on 0 Volts when you started and since VOLTAGE IS ELECTRICAL PRESSURE
you will observe on the following settings
1 Volt Per Division
1 Second Per Division
that your LINE / DC Volts has jumped up to 5 Volts in amplitude
Now.... if you had an AC Power supply
Step 1. oh..that's right you already have the scope
Step 2. Attach an AC Power supply that is set to 5V AC
you will now see a sine wave on your scope
the AMPLITUDE of the sine wave IN THE POSITIVE DIRECTION will be +5 V
and it will then go to 0 V and then to -5V and it will keep doing this
DO YOU UNDERSTAND NOW
the straight line indicates THE TYPE OF CURRENT
Straight Line = DC (aka, it has no frequency)
Squiggly line / Sinusoidal Wave = AC (it does have frequency)
THAT'S CURRENT
now.. Voltage is , HOW HIGH IS THE WAVE OR THE LINE ON YOUR SCOPE
SO.... he told you to FIND OUT HOW MUCH CURRENT IS NEEDED
Not what type
but HOW MUCH (this is measured in Amps)
you replied by quoting in Volts LOL
you said
5 V DC
so basically you just told him
I NEED 5 VOLTS OF DIRECT CURRENT
he is probably now going to say to you .... again
BUT HOW MUCH CURRENT DO YOU REQUIRE ?
or
HOW MUCH ... DC Current do you require ?
Your answer should IF CORRECT contain
A NUMBER followed by the letter A or mA
FIND THAT
what if dont have data sheet?
You can usually obtain the information you need from the company that supplied the component. Either from the product page, links on the product page, or by emailing the supplier.
So what if you have more then 1 LED. What if you are running 3 3V LEDs at 50 milliampes with a power supply of 3.7V
The easiest way would be for each LED to have its own limiting resistor.
You *can* have your LEDs in parallel so that they can share a resistor but this makes your calculations a little more tricky.
@@kitronik ok. If they had there own resister what would it be. And if I wanted to Dim the LED would I just add a higher resister
how can u know the current
Hi, the value of 20mA was taken from the datasheet for the LED. The voltage of the battery was known to be 9V and as 3V is dropped across LED, that leaves 6V. The resistor value was determined by entering these figures into the Ohm's law formula.
doesnt that mean that the higher the ampere is the lower the ohm value is?
Yes, if the voltage is fixed, for higher current (Amps) you will need lower resistance (Ohms)
Maybe i am stupid ! Ok , it s my risk . I ve bought some led bulb for my turn light motorcycle but doesn t sey what value it has , 5 W , 10 w ….
Is it possible to do like in your movie ?
So the voltage is 12 V , the current is 9Ah , and about the LED buld WE DON T KNOW ANITHING , just it works on 12V
12v battery what is led
What if the voltage is the same but Watts are different?
If you are dealing with power, then you will need Watt's law: Power (in Watts) = Voltage (in Volts) x Current (in Amps) P = V I
I hope this helps
@@kitronik So how do I find the resistance that way? I've got a canbus 12v bike where the computer can't see the bulb. That then bulb is 12v doesn't change anything. Standard W is 21/5. LED is probably 5 times less that. Does that mean 5 Ohms is fine?
@@bxbank Are you trying to change the bike light over from filament/halogen bulb to LEDs? It may not be quite as simple as installing a resistor appropriate for the LEDs. It depends on what the bikes computer is looking for to determine if there is a light present or not. I would try to get a hold of a diagram produced by someone who has successfully done this conversion.
@@kitronik no one has done it before. The headlights have been done but not the parking and taillights. That is what I'm trying to fix. both bulbs are 12v canbus error free but my computer doesn't see them. The only thing I know that's different is the wattage. It seems that can bus bulbs not only have resistors but also capacitors. I'm just not sure and again no one's ever done it. The bike is a 2007 BMW F800S. The gs911 cannot configure the ECU to say that the bulbs are LEDs. Only the indicators.
@@bxbank Having had a poke around on Google, mainly to find out what CANbus is, I've noticed that there are various resistor/adapter kits available for these conversions, including tail lights. There are a few on Amazon too.
I'm reluctant to give specific advice as I have zero experience to draw on but if I come across anything specific I will reply again. I'm sorry that I don't have a definitive answer for you at the moment.
So if I have a 12v 16a led toggle switch & want to wire to 120v cord I'd need a 6.75 resistor??
I'm a noob.. help me not kill myself
It'd need to be a very powerful (Wattage) resistor for that. I wouldn't want to recommend anything specific but would you advise you to get in touch with the supplier of the LED.
Im stuck ,are you able to help me please ?
What can we help you with?
@@kitronik would you be as kind as to double check my calculation please ,here are the details....
Battery 4.07v
LED 3v-3.7v & 2A-3A
Calculating using the lower 3v and 2a i make it a 0.85 ohm resistor is needed inline to save the LED from frying..
Seems to low to me and i feel ive messed up some how.
Its quite an expensive cree LED and i dont want to mess it if i can help it ..
Can you double check my calculation please and tell me how you done it ..
Be really greatful
@@kitronik Cheers for getting back 😕..
Can i send an email or call your shop ?
@@spoonerlee2908 Yep, give us a call or drop us an email, our customer service team are at the ready: Details can be found in the footer: www.kitronik.co.uk/
So basically you can't go further if the data sheet is not available... Or you will just be fumbling
As with any calculation, you need two of the values to calculate the third.
What if you didn't know the current?
Hi, in order to do this type of calculation, you need two of the three values. You can then determine the missing third value. I hope this helps.
Complete NOOB here. What if you are using a salvaged LED, which has no datasheet, how can you figure out the value, of the resistor needed? Also, if the current is reduced by the resistor, for the first component in the circuit [the LED], what amount of current will be left at the end of the circuit, if it's a more complex circuit, with many components and many resistors? Isn't the current reduced to nothing, at a certain point?
The .02A and the core voltage of 3 volts was poorly explained. You need to explain where the values came from
led is not of 3v its of 1.5 to 2 volts