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.

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4
votes
1answer
65 views

How can I ensure low-resistance ground contacts to an aluminum enclosure?

I am building an electronics project with an aluminum enclosure. I need to ground it—and very well—for human safety. (The system handles 300 A of current, and I want to be sure that if there is an ...
0
votes
1answer
87 views

Need To Understand Transistor Based Led Circuit

Which Transistor Topology Is Used in the Below Circuit & Why? Need to understand the purpose of zener diode (ZD2) with 12.5 Vz and R1 with 2k value? Why C1 & R2 is used for Q1 transistor? ...
0
votes
4answers
58 views

Basics physics question about calculating resistance

Why is the total resistance calculated differently when resistors are in parallel, compared to when they are in a series? For example, $$ \dfrac{1}{R_t} = \dfrac{1}{R_1} + \dfrac{1}{R_2} + \ldots + ...
1
vote
3answers
83 views

Increasing sensitivity for voltage measurement

I am trying to differentiate between two kind of marbles. I am using the marbles as a second resistor in a voltage divider and measuring the voltage drop on it. Theoretically there must be a ...
-3
votes
2answers
60 views

Why do RI=RL equal in maximum power transfer theorm?

I know mathematical proof I need explanation. Why this happen.That doesn't make any sense to me.I know that in series connection current (I)is same.But here  current flow is changing with different ...
0
votes
0answers
10 views

Power supply for a fan 12v [duplicate]

I not very good in electronics, I need to feed this fan 12mm, in the specification that requires 12v and 0.250Am. My question is if I can use a DC power supply 12v and 1,5Am i risk of burn it with a ...
0
votes
2answers
48 views

Get practial resistances for the Current Divider [closed]

My understanding The resistance as seen through the load is just Rs, Therefore 60K < Rs < 80K. Is (current Through Rs Resistance) IL (current through RL ...
1
vote
2answers
237 views

When conversing, what is a “big resistor”?

In casual conversation, what does "a big resistor" typically mean? Does it mean a resistor with a high resistance or a physically large resistor? Or, is this just bad terminology that should be ...
2
votes
2answers
241 views

Deciding On A Resistor For an LED

Let me preface: This is my first post on this exchange, so I will try to provide as much context as possible. If some details are lacking, or I've left this question overcooked, I apologize. So, I am ...
3
votes
3answers
188 views

Are there side effects to using too much resistance for an LED?

I have a 9v battery and a standard red led from reference 1.7v drop and I want it to draw 20 ma also from reference. so id need a 365 resistor. to my understanding if i have too little resistance then ...
1
vote
2answers
89 views

How to create a linear current response from a passive pot circuit?

I am wanting to linearise the current response of a circuit which currently has the resistance change from a linear pot. I have a current input that I want to test using a test jig/simulator. The ...
0
votes
1answer
81 views

Why DC resistance is used in MOSFET?

With mosfets there are two resistances called DC resistance Vds/Ids and AC resistance dVds/dIds at the operating point. I am wondering about the purpose of giving the DC resistance here? Where the ...
0
votes
2answers
52 views

AC source resistance problem while simulating transformer in LTSpice

I am trying to build a Voltage quadruple circuit. But as per my requirement ,the source I will be using has a resistance of 25 ohms.As the input signal to too small I need to use a transformer to ...
0
votes
0answers
89 views

Non-Ohmic Internal Resistance

How would a non-ohmic internal resistance to a battery change the voltmeter reading in this (hopefully correctly drawn) diagram?
3
votes
2answers
278 views

What does impedance control on a PCB mean [closed]

I understand that when the electrical length is less than 1/10 of the trace length I would have to go in for impedance matching. A PCB impedance is controlled by its stack up. THat is thickness of ...
0
votes
2answers
63 views

Capacitor charging

I am stuck at this question. A battery of 9 V charges a capacitor of 47 uF through a resistor. What resistor value needs to be used to obtain a voltage across the capacitor of 8 V when 10 seconds have ...
0
votes
1answer
86 views

Circuit that would meet this requirement

A radio needs to be tuned to a range of values between 526.5 - 1606.5 kHz. Choose a combination of inductor and variable capacitor values within a tuned circuit that would meet this requirement. ...
0
votes
2answers
25 views

Resistance network

I'm looking to create a circuit which will be used to test external PCBs. One of the external circuits features four switches with three resistors in what I believe is known as a resistance ladder (or ...
-1
votes
2answers
51 views

What does will happen in real and written?

Explain please i'm confused :/ What would happen if a wire having no resistance were connected directly across the terminals of an 8V battery? How much current would result, according to ohm's law?
0
votes
2answers
58 views

Equivalent resistance of resistors

Can somebody help me solve this. I need to find the equivalent resistance of these resistors. I really don't know where the trick here is. If somebody could help me I would really appreciate it
0
votes
0answers
41 views

Can a Dummy Load be Used as a Resistor?

I know this sounds like an obvious question, but I just want to make sure, but can 10 ohm dummy load be used as a resistor?
0
votes
1answer
53 views

Calculating resistance with a multimeter

I recently took on the job of working on someone's amplifier. There was a burnt smell coming from it. I found the pieces of the puzzle that were fried and replaced the ones I could, two diodes and two ...
-7
votes
1answer
39 views

How to calculate what resistors are needed for a specific voltage output, when using a variable regulator [closed]

I am using the LM1117, I need to generate 2 voltage rails, 1.32V, 3.75, but have no idea what level of resistance is required to generate them, is there a equation to work this out?
0
votes
1answer
54 views

Voltage and Amperage for LED Cube

I'm setting up my led cube and wanted to test with a few extra leds before hooking up my time intensive cube. FYI I am a computer scientist not an electrical engineer. I would like to make sure my ...
0
votes
1answer
34 views

Dual Fuel Senders - Shared Fuel Gauge Circuit Help

Just planning should I ever convert a car to run dual fuel i.e. Petrol and LPG/Autogas and decided I don't much like the way the gauges are done in most installations, so I decided I wanted to find a ...
-5
votes
1answer
76 views

How to reduce resistor heat? [closed]

I have 240VAC main and from 2 sides of wire 2 resistors 1W 33k... After some time resistors heat up. I don't know why is that? By my calculation, when I have 1 resistor on 120VAC, then power of 33K ...
0
votes
2answers
100 views

Is the use a very small value resistor negligible?

I made a simple LED circuit for a hobby project. It uses a cellphone charger rated at 5V. There are 2 LED's rated at 700mA at 2.4 V in series. The calculated resistance for my current limiting ...
0
votes
1answer
71 views

Output resistance of a BJT in saturation

It seems by the characteristic curve of a BJT, that it behaves as a resistance in saturation region. Is this conclusion true? and if so how can I calculate this resistance (seen from collector) ...
1
vote
0answers
67 views

Finding Values of Rd and Rs to satisfy the N-MOSFET design

I've been stuck on this design problem for a while and I am just filled with a lot of equations and unknowns and not getting anywhere with it. Here's a picture of the problem with the problem ...
3
votes
1answer
61 views

Calculating resistance for piece of metal

I have very poor understaning of electricity and usually go for "water analogy" (or Ohm's law) but it seem to have no use here: I need to calculate a resistance of a metal disk with given diameter, ...
3
votes
2answers
77 views

What determines the amount of current that can be drawn from a generator?

I tried searching this site and the internet for answers to my questions but found only partial answers. I am experimenting with generator design. I am using only one pole of the magnet so as to get ...
0
votes
1answer
72 views

Upgraded 10 turn potentiometers don't work whereas the original 1 turn potentiometers do. Why?

I bought this adjustable power supply kit and successfully assembled it. I wanted to upgrade the potentiometers to 10 turns so I could have fine control over the current and voltage limits set. Both ...
2
votes
4answers
86 views

What is more accurate, thermistor's R-T table or Steinhart-Hart equation?

If I want the conversion of thermistor's resistance to temperature to be as accurate as possible, should I refer to a table or use the Steinhart-Hart Equation? I am in doubt because a table contains ...
29
votes
8answers
2k views

Two black boxes display the same impedance at all frequencies. Which has the single resistor?

Two black boxes display the same impedance at all frequencies. The first contains a single 1 Ohm resistor. Each end is connected to a wire, so that two wires protrude from the box. The second box ...
6
votes
2answers
1k views

Does skin effect appear in home wires?

A technician said: Its better to use a solid cables for homes (not stranded cables). I did not use any calculations but I think that stranded cables are better due to skin effect. We use 220V / 50Hz. ...
0
votes
4answers
74 views

How do I find the equivalent resistance in this circuit?

I'm so confused on how to find the equivalent resistance of this circuit. Initially, I calculated it to be R_eq = (1/(42+21)+1/63+1/(84+105))^-1 = 27 Ohms, but I think that's wrong. I think that the ...
3
votes
3answers
291 views

If the voltage doesn't kill you, does the current capability matter?

Trade electricians often work on live household circuits carrying 120V AC. I've gotten shocked by accidentally touching such hot wires often enough to recognize the 60Hz AC buzz. Fortunately, human ...
0
votes
2answers
76 views

What is the equivalent resistance of the circuit below?

I want to use a method to simplify this circuit to reach it's equivalent resistance.Do you have any idea?I don't want to use directly mesh and node method.
1
vote
4answers
90 views

Variable Resistance

simulate this circuit – Schematic created using CircuitLab This is a pulse generator, outputting square pulses with about 8% duty cycle. Tuning R2 down to 120k will result in the same ...
1
vote
1answer
171 views

Have I damaged my multimeter by applying voltage in resistance mode?

I have an VC97 digital multimeter. In resistance mode, I applied the multimeter leads to a battery with a 4.2V charge. I did this twice, and also did so in capacitance mode. I didn't notice any ...
2
votes
1answer
50 views

Method and probes for measuring resistance of conductive braiding?

Looking for advice on a method to measure the resistance of a piece of conductive braiding. The braiding is a metal plated material; it's flat when pulled taut and expands into a cylinder when bunched ...
2
votes
1answer
83 views

Plane Resistance with Vias

I have a long and wide power trace (0.3" x 3") that is duplicated on several layers of a PCB. For some thermal purposes, there are many thermal vias punched into the trace (See Figure below). I ...
0
votes
2answers
75 views

Circuit analysis (Intro to Parallel Circuits & Series)

We are just in the beginning phases of learning how to simplify circuits by finding equivalent resistance. I've gotten every problem right except for this one. The answer says its 2000 ohms, but I ...
0
votes
1answer
103 views

Can I ignore resistor for IR LED?

I have two IR diodes and I want to connect them to my Raspberry Pi. From Pi I have 3.3V voltage. Diodes are TSAL 6200 . Can I connect them to PNP and my PI without resistor safely with this wiring?
2
votes
1answer
35 views

AC analysis: finding L and R

EDIT: there should be arg[I2] instead of arg[I3] I've tried to replace V1, C1, R1 with Thevenin equivalent, but I've lost in my calculations. Is there any better approach?
0
votes
2answers
107 views

heating a 5 ohm resistance with a 9V Battery

Hi I am working on a project which involves heating a resistor with a 9v battery. I am heating resistance because I want to increase the temperature of a temperature sensor so that I can do something ...
0
votes
1answer
142 views

Finding the equivalent Resistance of acircuit

simulate this circuit – Schematic created using CircuitLab I am a little confused on how to find R equivalent of this circuit because of the wire. Right now I have the following ...
-2
votes
2answers
47 views

Led matrix display atmega32

I need help with an LED matrix I am building for my son, running from an atmega 32 and a BC818 transistor. I have the schematic from http://dhassel.de/projects/cool/led-matrix-display/ In the ...
0
votes
2answers
65 views

Calculated resistance of an LED [duplicate]

I am working on some circuit lab homework this week and am a bit stumped by something I just can't seem to find anywhere in my Circuit Analysis I book. The lab has me construct the following circuit ...
0
votes
1answer
56 views

Input Resistance vs Output Resistance

I am having trouble understanding the difference between these two concepts. I know that input resistance is the resistance looking into the input terminals and output is looking into the output ...