I recently got a pack of different value resistors, but some of them were zero ohms. Is there any purpose in using 0 ohm resistors?
65986
I am new to PCB design and I noticed that some schematics use 0Ω or 100mΩ resistors. What is their purpose and why do we need to use them in our PCB design?  Normally if we wish to probe how much current the load is taking, we put a jumper pin across the PCB trace (then measure current across the pin using a multimeter). Adding resistors for this purpose seems like it would waste a lot of PCB real-estate. Is this the sole reason why 100mΩ resistors are being placed (since I = V/0.1Ω) instead of a jumper pin?   If so, is there any consideration we should take when placing such a mΩ resistor on board so it doesn't affect the signal or behaviour of the circuit?
97571
I know this has been asked time and time again but bear with me as I am struggling to understand, so say I have this simple circuit here   with 120v (dc for simplicity) as the input voltage and I have an led that runs on 3.4v and max 20ma ohms law states I=V/R so R=V/I, so R=120v/0.02a = 6000 ohms or 6k is this correct? how do I know the voltage drop across the resistor is correct, and what about power dissipated by the resistor? also, Is there an easy way to calculate everything at once?
79810
I know the path of least reisistance has been clarified already However, to derive the equations you need to assume that the voltage of each parallel component is equal. But we know for a short circuit current the voltage is zero (By Ohm's law!) So there is a glaring contradiction!
82394
What is the value of Vout if we know the value of Vin in this case?    It is a buffer amplifier, but it has two extra resistors so I think that the gain is smaller than 1, but how small?    (Vin-V3)/R1=0 &lt;=> Vin-V3=0 => Vin=V2=V3  (Vout-V2)/R2=0 &lt;=> Vout-V2=0 => Vout=Vin=V2=V3
91421
I want to know the function of the three 1Mohm resistor between the HVDC+ and HDVC-, they are R4 R14 and R17 in the below circuit, thanks for your attention and time!
95325
I have a power supply of 5 volts @ 1A. I want to reduce the current from 1A to 250mA. Which resistor should be use?   I tried this equation(Ohm's Law):  R = V / I  = 5/(0.75)  = 6.66 Ohms.  I tried the 6.66 Ohm resistor but it only reduce few mili Amps.
99644
states that the relationship between current ( I ) voltage ( V ) and resistance ( R ) is  $$I = \frac{V}{R}$$  However  cause the resistance of a material to go to zero, and as I understand it, as $R \to 0$, $I \to \infty$. Does this present a problem for Ohm's law?
48628
I'm taking an electronic circuit analysis class, and I was asked to give the color of the 3rd band of a 1MΩ resistor. My answer was blue, thinking it could be black-brown-blue (01 * 1MΩ), but the automated quiz said the correct answer was green (brown-black-green).  So I did some research, thinking there were just multiple correct answers, and I read in a few places that the first band on a resistor is never black (0). Why is this? Does a black first band have some other meaning? It would really help me remember it if I knew the history or reasoning behind it.  This question has been answered. For further reading on zero-ohm resistors mentioned in the answers and comments here, I found these questions and answers helpful:
83528
I want to join 3 resistors connected in parallel into one. Like this   If for the total resistance I use  $$R_t = \frac{R}{3}$$  But what about the power of them?
113882
I have faced a few instances in which I need to measure resistor or capacitor value which is soldered to the PCB board (SMD component). These are very small and difficult to look the value written on it. When I measure using a multimeter I am not getting the correct value (maybe due to other components connected to it).   Is there a way by which I can measure the component's value without desoldering it?
10683
Is there anyway I can connect resistors to allow them to take more power such as using 4 1/4 watt resistors to get a 1 watt resistors. Or do i just have to use 1 1 Watt resistor.
101720
I've been a programmer for years but am very new to electronic engineering. So far I see people saying it doesn't matter where a resistor goes in your LED circuit as long as it is present, but it sounds like that's the nature of the basic LED circuit.  When does the placement of a resistor start to become important?
3926
I have seen many resistances with difference Wattage i.e 1/4W, 1/2 W, 1 W, 2 W ,3W etc. If I have 3 W Load which is an (large 3W) LED in my case, which Resistance should I use?  Also The LED I am using needs 3.5V DC and 0.8 A current. I have a Battery which outputs 8V. How can I calculate the Value of the resistance which can drop 8V to 6V?
106171
If amps = volts / ohms, and ohms is 0, then what is x volts / 0 ohms?
82934
Very newbie question here...one to which I've been unable to find an answer in any of my books or online resources.   Whenever I see a capacitor/resistor assortment that features the most "common" ones (which, I understand can be quite subjective), they tend to come rated in powers of 1, 2.2 and 4.7. What's magical about those numbers?   Is that some mathematical relationship in Ohm's law of which I'm not aware? Is it some logarithmic progression for some OTHER electrical engineering formula that I've not yet encountered? Why is there such a huge gap between 4.7 and 10.0, why isn't there a 7.1 or some such? As someone who a scary uncanny knack for solving "find the pattern in this series of numbers" puzzles, it's killing me that I can't figure this one out. :)
8513
I have been looking around for an easy way to convert 12V to 5V. I have seen some people saying that a simple resistor is all that is needed.  $$ Volts = Ohms \cdot Amps $$ $$ Amps  = \frac{Volts}{Ohms} $$ $$Ohms  = \frac{Volts}{Amps}$$  So applying a resistor will diminish the voltage of the circuit. That should mean that an appropriately sized resistor could simply be placed in the path of a 12V circuit, converting it to 5v.   If this is the case how would one reduce amps? Would series vs parallel make a difference in this area?   I have seen designs that include a regulator IC and some capacitors, but if a simple resistor/fuse/diode setup will do the trick, I would really prefer that.
78789
How anyone know how to do the question? I know how to reduce it to a window pane of 6/6/6/6 with a 3 in series but i have no idea how to do it.  Well i did manage to reduce the right side of the circuit to a pane of 6/6/6/6 and am unable to determine if its a Wye-Delta transformation (probably not) and I do not know which of the resistors are in parallel and which are in series.  Answer should be 4/3V   (The website which the answer was hosted initially no longer exists)