It's a measure of how much an conductor opposes current flowing through it. It can also refer to a part of a circuit, which has a non-negligible resistance value.

learn more… | top users | synonyms

0
votes
4answers
61 views

How can you measure low resistance accurately?

I got resistors having 1Ω and 0.1Ω. They will be used for measuring current incident to MCU. But when I tested the resistance by using my DMM, the value was fluctuated a lot and it was never what it ...
-1
votes
0answers
67 views

Op-amp circuit problem - input impedance and its components

I need help in solving this op-amp problem. For the circuit on picture (op-amp properties:IN impedance is infinite, OUT impedance is equal to zero) determine the input impedance and discuss the ...
0
votes
1answer
37 views

Opposing EMF's with an odd change…?

A conductor in case 1 has two separate uniform magnetic fields \$B_1\$ & \$B_2\$: The magnetic fields(the blue rectangles are the field regions parallel to the conductor, while X's are the ...
-1
votes
1answer
41 views

What is small-signal resistance of MOSFET?

In a NMOS transistor, we have a current formula for saturation region. $$I = \frac{1}{2}(\mu_n)(C_{ox})\Big(\frac{W}{L}\Big)(V_{GS} - V_{TH})^2$$ We bias the MOS with a \$V_b\$ in order for the ...
0
votes
1answer
41 views

is it possible to connect ac power source to battery in parallel connection ?

Is it possible to connect ac power source & a battery in a parallel connection where a battery is low voltage & have current more then the internal resistance of circuit ? As the battery is ...
0
votes
1answer
24 views

Choosing the correct thermistor

I need help choosing a thermistor. I’m not sure what I need to look for. Let’s say I have this circuit measuring temperature: I have a range of temperatures from 0 to 10 degrees that I need to ...
0
votes
1answer
128 views
+50

How to calculate the induced voltage?

From the given diagram: Conductor(C) is the only movable part with given velocity (v), connected to a stationary terminals(top & bottom) and an exterior circuit with a load. Will current flow ...
1
vote
1answer
56 views

Earphone cable resistance [closed]

Earphone cables are usually very flexible - does anyone know how much resistance they tend to have? Are they cable of carrying 2A at 5V? My guess is that they are copper strands, but I'm not sure how ...
2
votes
1answer
160 views

Calculating maximum power dissipation based on contact area between two metal conductors

I am trying to figure out how to properly calculate the minimum contact surface area based on the maximum required power dissipation. Let me explain.. I am creating a custom semi-circular metal tab ...
0
votes
1answer
52 views

voltage drop & resistivity calculation

I wanted to implement below formula into excel sheet. can someone suggest me with example. cable equation example : system voltage =12v, sys current=8A, length in feet=50. Resistance = resistivity* ...
0
votes
0answers
26 views

Dc electrical cable calculation [duplicate]

I wanted to implement below equation in to excel sheet. Please let me know how can i calculate the below equations. Cable online Can you explain in brief. Its bit confusing with equation. Just help ...
-1
votes
2answers
51 views

Powering a ESP8266 and an auxiliar device using a single power source

I am trying to connect two components to the same 12V/1000mA DC power source. The devices are 300mA/9V (D1, auxiliar device) and 500mA/3.3V (D2, ESP8266) respectively. See the diagram below: ...
-3
votes
1answer
60 views

how to design a rheostat which gives me fix 24V supply for different input of 24V,48V,110V,220V [closed]

i want a constant voltage output using rheostat. It can be any electronic circuit control or by appropriate tapping.
2
votes
1answer
55 views

Thevenin's Resistance

I can't understand why the answer is like in the picture and not R = [ ( 4 + 6 ) // 8 ] + 2. Isn't 4 in series with 6 and parallel to 8 ?
1
vote
1answer
37 views

Finding the Thevenin equivalent circuit for the following one

From my poor drawing , it's obvious that the resistance between A and B terminal is just $$((((((100 || 100)+30) ||80)+20)||60)+20) = 50\Omega$$ But I am getting confused about determining the ...
0
votes
0answers
12 views

Datasheet MICS2614 - calculate sensor resistance R100ppb

The Datasheet of MICS2614 gas sensor shows the sensor resistance Rs/R100ppb over the O3 concentration in a graph. But as far as I can tell R100ppb is nowhere defined. The datasheet only shows R0 ...
0
votes
2answers
82 views

Calculating voltage in a simple circuit

If I had a 12V battery and wanted to use an LED that used 2V and 20mA, then I need a resistor that will drop 10V and provide enough resistance to produce a current of 20mA. Therefore I would use R=V/I ...
-4
votes
1answer
82 views

What are the resistances of the R1 and R2? How to compute? [closed]

This is transistor as a switch. I used KSP2222A transistor. How to compute the resistances! Thank you for any help.
0
votes
1answer
60 views

Insertion Resistance of Current Transformers

Given a current transformer like this: there is an insertion resistance that appears as a very small equivalent series resistance on the measured circuit. Since it is usually small (say, 0.0001 ...
0
votes
1answer
58 views

Why do we ignore parasitic capacitance in dc analysis of transistors?

Consider a transistor that has parasitic capacitance of the order of pico-Farads. Then at low frequencies, consider 10Hz $$X_C=1/(2\pi f C)$$ \$X_C\$ will be in the range of giga-ohms. ...
1
vote
3answers
89 views

dimming led with photoresistor

I want to dim a led in a circuit if there's less light. However, the Photoresistor I'm working with reduces the resistance when there's more light. How can I achieve the opposite effect on resistance ...
5
votes
6answers
1k views

Can I exceed the rated voltage of a motor if I limit its current?

I have a mini motor that's rated at 3 volts. Does this mean that the 3 is the number of volts that will produce the desired amperage for the motor? Could I technically make it work by plugging it into ...
0
votes
0answers
47 views

0 to 152 Meg Ohm resistance increase circuit

Trying to make a circuit that, at 2 Ohms per second, increases resistance from 0 to 152 MegOhms I have tried dual transconductance amps balanced with a timer. There was a micro controller presented ...
0
votes
2answers
33 views

Equivalent Resistance Calculation

Is it 5 // ((1//2) + 3)? So the 5 is parallel with 3, which is in series with a 1 parallel with 2? Right or wrong?
8
votes
5answers
484 views

Why does reflection only applies to transmission lines?

Why does the concept of wave reflection seem to only apply to transmission lines? For example, for a simple circuit with two resistances R1 = 50\$\Omega\$ and R2 = 75\$\Omega\$, is the voltage wave ...
1
vote
2answers
23 views

Cermet potentiometer temperature coefficients

I'm engineering a system that is temperature-sensitive, between ~-10-30C. I've moved to using cermet potentiometers because of their sub-200PPM/C temperature coefficients. If I wire such a pot with ...
0
votes
1answer
48 views

Toubleshooting PCB circuit - strange Zener diode behaviour

I have two units of a device which I shall call deviceA and deviceB. DeviceB is malfunctioning. Therefore I compared the resistance values of the same components on the boards of both deviceA and ...
0
votes
2answers
33 views

Losses in wire with varying cross section along its length

Say I have 5 meters of thick wire (10 sqmm), and for the last couple of centimeters, I have to use a piece of 2.5 sqmm wire for mechanical reasons. When sending a large amount of DC (say, 30 A) ...
0
votes
0answers
36 views

Change range of output values of potentiometer

I would like to use a fuel gauge in my car that expects 240 Ohms when the tank is empty and 33 Ohms when full. However, my current fuel sending unit reads 168 Ohms when empty and 34 Ohms when full. ...
0
votes
3answers
155 views

Why the diode has higher impact on dc characteristics than ac?

Consider this circuit which consists of a DC bias and an AC source connected with a diode and resistor: Source: Boylestad and Nashley book 11th ed. Using superposition theorem the circuit was ...
1
vote
1answer
41 views

dropping a signal voltage proportional to signal

Basically i have a car that im installing at aftermarket ecu in, The tps signal is normally a 0-5v signal (varible resistor on a 5v output from the ecu) that the ecu uses for various things, However ...
0
votes
1answer
33 views

Does wire gauge significantly impact the charging rate of smartphones?

This article claims that wire gauge in USB cables significantly impacts the charging rate of smartphones: USB cables have a data wire and a charging wire within the cable itself. Most USB ...
1
vote
4answers
123 views

What Happens to Unit If We Divide Two Resistance

My question is very basic. I have a resistance circuit in which two resistances of 2 ohms are connected in parallel. I want to find the equivalent resistance. I know the equivalent resistanve will be ...
2
votes
2answers
161 views

What is the resistance of a typical PCB?

What is the typical resistance between two points on a "typical" PCB? Let's say the points are 1mm apart and let's assume a normal office environment. I've noticed that resistors come in many values, ...
0
votes
1answer
68 views

Testing Amps And Resistance On PC Case Fan

Context: I'm wanting to tinker around with some mini solar panels to power some old PC case fans I have laying around. I know that case fans are generally 12v so I was thinking of running some 3v ...
0
votes
1answer
80 views

AC Wire Resistance

I stumbled across some unexpected data points when measuring the AC resistance of magnet wire. I varied the frequency of the AC voltage and measured the corresponding impedance of half a meter of 32 ...
0
votes
0answers
28 views

contact resistance

AZ2150 is a power relay that is rated for 40A at 240VAC. It has a contact resistance of <20milliohms initially. After use they say that typically the contact resistance will be between 20-100 ...
0
votes
1answer
41 views

additional resistance required to produce a potential drop

A wire of length 100cm is connected to a cell of emf 2V and negligible internal resistance. The resistance of the wire is 3Ω. The additional resistance required to produce a potential drop of 1 ...
0
votes
2answers
69 views

What is the best way to configure an electric fireworks igniter

I've seen a bunch of tutorials on creating a fireworks igniter using, a resistor or a piece of copper wire and a 9 - 12 v battery. Basically you the resistance from the small piece of copper or 1 ohm ...
-4
votes
4answers
102 views

Why do wider cables have lower resistance if parallel resistors in general increase resistance?

So given two resistors both with resistance R, the resistance they would have in parallel would be R*R/(R+R) right? For large R, R^2 increases like a square and 2R increases linearly, so there must ...
0
votes
0answers
41 views

Nichrome or Kanthal wire specs for kiln

I plan to build a kiln that can achieve 1000C - 1100C in temperature. I bought a PID controller and SCR voltage regulator to control the temperature. But I want to know if there is a detailed ...
5
votes
2answers
219 views

Does the Y-Δ transform suffice for every resistor network?

Suppose I have a (finite of course!) network of resistors only. Is it always possible to calculate the equivalent resistance between any two points using only parallel, series, Y-Δ and Δ-Y (wye-delta ...
3
votes
3answers
222 views

Why is the impedance in the parallel resonant circuit maximum at resonance?

Why is the impedance in the parallel resonant circuit maximum at the resonant frequency? For example if we have two resistors in parallel the equivalent resistance is less than the values of the ...
-6
votes
1answer
65 views

What happens if an electric circuit has 99% resistance? [closed]

What happens if an electric circuit has 99% resistance? What if you let electricity come out of a the negative terminal, and only the tiniest bit of electricity comes back through the positive?
0
votes
0answers
25 views

What are resistor actually? [duplicate]

I know that resistor resists flow of electrons from one point to other. I can understand the working of capacitor and inductors which are based on properties of magnetic and electric field . But what ...
2
votes
2answers
98 views

A theoretical question on probe resistances for a voltage measuring device

As seen in the figure above, a current regulator is providing a constant current looping through the series resistor Rshunt. Input impedance of data acquisition device is 10 GigaOhm. Can we say that ...
0
votes
2answers
83 views

How to measure resistance

I have a project to build heating element using silver ink. My specification is the heating element must be in range 2 to 2.6ohm I will design the circuit for the heating element, but have a problem ...
0
votes
2answers
88 views

Resistors and capacitors calculation for 555 timer circuit

I am new to electronics and I want to try an experiment. I want to use a 555 timer to create an automatic food dispenser for my aquarium (something like opening a small door when the timer has ...
0
votes
4answers
562 views

What is the total resistance of a LED array?

First time poster and a hobby EE enthusiast here. I want to turn on a LED array with a transistor switch and I'm having trouble with determining what will the total resistance on my transistor ...
0
votes
0answers
30 views

Calculating DC resistance from p.u. impedance

I need to calculate or approximate the DC resistance of a 208.5 km overhead line which has the following information: impedance per unit on 100 MVA base: R = 0.004 X = 0.047 B = 1.049 Is it even ...