The ohm (symbol: Ω) is the SI derived unit of electrical resistance, named after German physicist Georg Ohm. Various empirically derived standard units for electrical resistance were developed in connection with early telegraphy practice, and the British Association for the Advancement of Science proposed a unit derived from existing units of mass, length and time, and of a convenient scale for practical work as early as 1861. As of 2020, the definition of the ohm is expressed in terms of the quantum Hall effect.
I have gotten access to a large bare silicon die (almost 1" across, 14nm process) that my company gets from a fab. I've been monkeying around with an ohmmeter placed at the top of the die, with the test leads placed at various points around the die, and I almost always measure the same value...
So if I have a source of 5V and 20 amp then the maximum power I can get from the source will be:
$$ P_{max} = 5*20 = 100W$$
but my load can only take in 5 watts, it will blow up. But, does this have to happen or does my load only take what current it needs? My guess is that the load takes in...
Homework Statement:: How can I determine whether my basic circuit will work? A battery and two light sources.
Homework Equations:: conceptual question, use basic ohms law, current law, voltage law, etc.
This is not a homework question, i am just trying to understand electronics better. I am...
Hello everyone new here :)
I've recently enrolled myself in a computer technician course and I've encountered a few (basic) electrical sums.
I have absolutely no electrical background, and the course mentioned no requirement of such, but I'm already being presented with work I have no idea of...
Homework Statement
For an engineering assessment (first year with no electrical background), we are using a solar panel to power an element for a distillation system. we have calculated our heat energy output requirement that we need from our heating element as being 800 J/s. For simplicity we...
edit: The key thing I am after is why the ferrite might be responsible for the increase in resistance I measure on the coil.
Hello,
i have a coil designed to be 2.2mH and54 ohms. When an MN60 ferrite (T-ish core) is used with it, the inductance rises to 6.1mH as expected, and the resistance...
Homework Statement
1. Use resistors of 30 ohms, 40 ohms, 50 ohms, and 50 ohms to create a circuit with a total resistance of 95 ohms.
2. Find the amount of current going through two of these resistors if the circuit is attached to a source of 12 v.
3. What would be the voltage drops for the...
Homework Statement
We were given five samples of nichrome wire, each with a different diameter but the same length. A micrometer was used to measure the diameters. We then measured and recorded the electrical resistance, R in Ohms of each nichrome sample with a DMM. I will try to summarize all...
I have a DC powered pump, that has suddenly stopped working.
During troubleshooting I came up with the following results, that I just cannot reconcile:
Input wires, not connected to pump: 12v
Input wires connected to pump: 0v
Sounds like a short in the pump right? However, connecting the...
So, I recently joined a stargazing club, and for our summer activity, we're supposed to use a telescope, a photoresistor, and a multimeter to measure the luminosity of the moon. I know that luminosity can be calculated with the equation, L = σ AT 4, and that brightness can be measured with the...
Homework Statement
A student is calculating the resistance of a piece of fuse wire. He takes 5 readings on the voltmeter and ammeter for different settings of a variable resistor.
He decides that instead of measuring the gradient of the graph to calculate the resistance, it would be okay to use...
Homework Statement
Hello.
The resistance of a wire increases when the temperature increases.
How would this cause the shape of the graph to change? Explain why. The graph shown is a straight line graph with the line traveling at 45 degrees path. The x-axis is VOLTS. The y-axis is CURRENT...
I'm not sure if corrosion does have a significant effect on copper in general but if it does, how and why does it happen, and the process of it happening and its effect on the overall resistivity?
This is for a physics assignment...Please help if you can.
Thank you
The electrical resistance of a wire varies directly with the length of the wire and inversely with the square of the diameter of the wire. If a wire 50 feet long and 2 millimeters in diameter has a resistance of 0.265 ohms, find the length of a wire of the same material whose resistance is 0.068...
Hi, i didnt know where to put this question cos its kind of multitopic, here is why...
I am working on a better way to take mechanical energy from muscles, i made a teste bench for pedalling in very different ways, including traditional(circular) pedalling, the thing is. I am measuring the power...
I've been trying to brush up on my electrical engineering skills and have been working on the circular and redundant terminology of amps, volt, ohms and watts.
It seems to me it all comes down to a quantity of electrons (i.e. coulombs).
And, for various reasons perhaps the number of electrons...
Hi,
I am in fact quite new to these forums but have been lurking for a while. I am trying to design a OLED reader that will display the watts, ohms, and volts after being read from a circuit. Almost exactly like this:
Any ideas on where to start? I am not necessarily a novice when it comes to...
I am working on a small project and having those values shown in real time on the device will be helpful. I don't have much room as it is. I currently have one of those little 1s-6s volt meters used by RC hobbyist and use my multimeter to check resistance. My goal is to have something around...
Homework Statement
Using Ohm's and Kirchoff's Rules find the unknown resistance Rx
Homework Equations
V = IR
Sum of currents at a node is zero
Sum of voltages around a loop is zero
The Attempt at a Solution
For the 2 ohm resistor I found the voltage to be 4V by the formula...
At high school we were taught basic circuit formulas such as V=IR, P=IV etc but now I am studying circuits in Engineering (at university)
we have been introduced to the techniques of nodal and mesh analysis.
My question is, when and why do we use these techniques rather than the...
so if i have 89.6g water at 304K and a constant p=1.00bar and i heat it by running 1.75A through 24.7 for 105 seconds what will the final temp be?
im thinking i can take q=mC(Tf-Ti) and q=IT and I=R/V
to say that Tf= (Rt/vCm)+Ti
i can't rember that much about physics and this stuff...
Brief personal intro, I have last time studied physics about 12 years ago.
I am now starting in 2 weeks time in a university and there is mandatory physics course so I am trying to relearn and learn as much as I can before that time.
For that reason I am trying to solve textbook tasks...
Omggg :( Determining voltage between point a and b given R = 40 ohms
This is what I did for part A:1) ΔVrms = Vmax(1/√2)
ΔVrms = (145)(0.707)
ΔVrms= 102.53
2) Ztotal = √[R² + (XL - XC)²]
XL = 2πfL
XL = 2π(40)(185 x 10^-3)
XL = 46.49
XC = 1/2πfC
XC = 1/[2π(40)(65 x 10^-6)
XC =...
Homework Statement
Using all the following resistors : 2 x 12 ohms , 2 x 24 ohms , and 2 x 36 ohms. create a circuit where the total resistance will be 4 ohms.
The problem states that I have to use ALL of the resistors..making it so complicated
Homework Equations
1/Req = 1/R1 + 1/R2...
I have a solar cell that is rated 3.6 amps .5 volts 1.8 watts when you take a ammeter it does put out 3.6 amps, but this is basically a dead short reading. What I want to know is these cells put out .5 volts using ohms law how much resistance is needed to have a voltage output of .3 volts so you...
I recently learned that ohms law is not always obeyed. I found this surprising because I thought ohms were defined in terms of volt and amperes by the equation R=V/I. I did a little googling and found the following definition...
This clarified things a little in that the definition of an ohm...
We have all seen Ohms law, J=σE. This approximations makes sense in simple electric fields in which the charges are accelerated in parallel.
However as I will demonstrate, this implies a few conditions on the charge density (ρ) associated with the current density (J).
Now, from the continuity...
Look at the attached problem with solutions. I don't understand what the author means in c) when he says that succesive shells contribute less and less because the cross sectional area grows proportional to r2. The flux through a closed surface is always the same (Gauss' law). Rather the reason...
Here is my question: When I look a p.d divider circuit I get slightly confused, because the way I was reading the explanation it says: that when the a thermistors has 0 resistance it has 0V across, so when the resistance increase the voltage increases and the will turn on the base emitter to...
Okay well my issue is from a basic problem. The problem is you are given an unlimited number of 10 Ohm resistors. They can only handle 1 watt of dissipation and you need to create a circuit that has a total resistance of 10 Ohms, and has a power dissipation of 5 Watts. They are actually looking...
Homework Statement
Hi, I'm asking the usual "what formula gives me these results" question, but with a twist; I'm attempting to make a "virtual" analogue multimeter that replicates a physical piece of equipment, for training purposes. The idea is that a random MegaOhm value will be generated...
Does Ohms Law have practical limits?
For example:A piece of steel wire of length of length 10um and of CSA 20E-10.
Can we calculate the resistance of such a tiny piece of wire (resistor) in the usual way?
thanks
Hello, I am trying to get my head around biasing.
I do understand the principles.
In the attached circuit the Collector current is 2.5mA and the collector resistor is 1K. Therefore my circuit here is biased at 2.5V. The power supply is 5V.
So that would give a 2.5V drop over the collector...
1. Write the equation for each run in the form (potential=constant x current)
{the form has two numerical list to work with}
2. How do I find the constant from these 2 lists? Is it the correlation that the question is looking for? or, Is it OHMs constant, that the question is talking about??
A colleague and I are looking at modelling a hot electron beam hitting a initially charge neutral plasma. Initially we're looking at the 1D problem, the equations we're using are:
\begin{array}{rcl}
\gamma^{3}(v/c)\left(\frac{\partial v}{\partial t}+v\frac{\partial v}{\partial x}\right) & = &...
Hello, I feel like an idiot because I can't answer this myself (I forgot my high school physics).
I have a stereo amp head that has two speaker outputs at 75w each. Each of these outputs has a resistance of 8 ohms each. My cab, however, is mono, and only has 1 speaker input. The cab I own is...
Homework Statement
This is not exactly a homework problem, but it's one that marks me as a beginner: is there an intuitive physical understanding, using dimensional analysis, of the unit combination making up the "ohm"? I don't mean a physical understanding of resistance--that's not a...
Homework Statement
See picture.
Homework Equations
Ohms Law-V=IR
The Attempt at a Solution
i do not know what to do once i find Rt (8.714...) because there is a parallel and a series in this circuit...
I've never really understood the relationship between voltage, current, and resistance. The more I read about them, the less comfortable I feel discussing them. V=IR...mathematically, it doesn't get any simpler than Ohms Law, yet when I try to predict the behavior of its variables in real world...
Thermistor Temperature- Ohms Law??
Hi All!
I am trying to convert a current of 795mA to a temperature in degrees celcius but I don't understand how to do it.
I realize that Ohms law of V= A/ R is involved somehow but that's the extent of my knowledge.
PLEASE HELP!
I have also been...
we learned it could be a trade off between loss and flexibility. Because if it was around 50 ohms or so it would be too thick of a wire.
and the we learned the minimum loss is around about 77 ohms.
What do you guys think.
i have attached a picture showing the problem;
just wanting to know if my working out and reasoning is correct please.
http://img29.imageshack.us/img29/5412/questionsq.jpg
The Attempt at a Solution
i have used KCL to answer (a) and (b) and have answers 0.6 and 1 respectively.
for (c) and (d)...
What does increasing the frequency of a computers main bus [the bus that connects the CPU to the chipset] imply about the voltage ["information"] traveling on a bus? (what IS the frequency of a bus effectively measuring, data units per second?)
The way i see it (please correct me if I'm...
Homework Statement
A 1 mile long copper wire has a resistance of 68 ohms. What will be its new resistance when doubling it over and using it as "one" wire
Homework Equations?
R=V/current
The Attempt at a Solution unable to attempt, I know that when it is cut in half R=34 ohms
can someone please explain to me physically how is it that
when i have an AC source and i measure Voltage on a resistor its the same with and without the resistor
and when i have a DC source and i measure Voltage again on the resistor and now there's a different reading
its like ohm law...
Hello
I'm trying to get my head around ohms law, and have a question.
If I have a motor that draws 12volt 100amp, and I would like to drop the amps down to 30, would I put a 360ohm resister in line.
12 * 30 = 360
V * I = R
Side note can you get a resister that is 480 watt...