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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2answers
77 views

How does Current relate to Voltage in their behavior in our physical world

I'm really an electrical noob who tries to understand voltage, current and resistance. I know the formulas and can somehow come up with basic explanations about the physics of electricity. However, ...
0
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1answer
43 views

How was Vc(t) found in this source free RC circuit?

Shuldn't \$v_c(t)\$ be the same as \$10^4\space i_s\$ after \$t=0\$?
0
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2answers
56 views

Copper brushes?

I noticed the superior choice would be a carbon based brush,however, is pure copper brush a bad choice? I'm considering copper due to the lower resistance and higher current carrying capacity. I ...
0
votes
1answer
64 views

Resistance of twin core wire

I'm trying to do a problem for revision and I'm running into problems calculating the resistance of this circuit used to approximate a twin-core wire. It's used later in the question with the middle ...
1
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1answer
40 views

Calculating resistance of an electric brush

For a certain application, I'm using carbon based brushes to transmit power from a stationary component to a moving component. I'd like to calculate the resistance of the carbon based brushes to know ...
0
votes
1answer
46 views

Voltage divider with ADC

simulate this circuit – Schematic created using CircuitLab I am a newbie and this may not be a tough one. I am using Arduino UNO and trying to find the unknown resistance with the above ...
-1
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0answers
31 views

NEO 6M GPS Module: Resistance between pin 23 and 24

I bought a NEO 6m GPS module from China. It is not working properly so I visually checked it. It looks like pin 23 (VCC) and 24 (GND) of the NEO-6M chip are bridged, and I measure 0 Ohm between them. ...
-3
votes
2answers
97 views

How do I know if I need a resistor or not? [closed]

I have bought a Sound Bomb from Maplin. On the bottom of the device it says: Voltage (DC): 12v Voltage Range: 6-15v Current: 85mA If I want to wire this ...
3
votes
4answers
71 views

Why is resistance across my arm-span so much less than across my face?

This sounds like a strange question (it is) but, from a purely biological standpoint, why is the measured resistance across my hands (I measured 120k\$\Omega\$) so much less than across my face? I ...
0
votes
2answers
48 views

thermal glue or paste thermal resistance

Trying to calculate thermal resistance before heat sink for cooling MOSFET. MOSFET Rjc is given in datasheet. But heat sink will be glued using thermal glue like HC910 which has thermal conductivity ...
0
votes
1answer
45 views

Different amperage with a normal and a hook Multimeter?

I am measuring the electric power (P = VI) in a gear-motor. I measure it of two ways. One way is measure with a multimeter the resistance of the motor, then with V=RI, I measure the current, then I ...
0
votes
1answer
59 views

Build own custom USB 'regulator' adapter board to solve Desktop boot hangs with KVM

My Desktop PC hangs in the BIOS boot phase when my KVM is attached. If I unplug the USB connecting the PC to the KVM, the PC boots without hanging. If the USB of the PC is connected directly to the ...
0
votes
1answer
66 views

How to use an 2-axis accelerometer as a potentiometer? [closed]

I've got a couple of Memsic 2125 accelerometers around and wanted to try to use one of them to replace a pair of potentiometers in a circuit (x axis replaces pot A, y axis replaces pot B). How would ...
9
votes
3answers
121 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
118 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? ...
1
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4answers
65 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
84 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
67 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 ...
-1
votes
0answers
11 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
49 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
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2answers
240 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
245 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
201 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
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2answers
92 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
86 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
56 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 ...
3
votes
2answers
290 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
27 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 ...
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votes
2answers
52 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
61 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
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0answers
42 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
40 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
57 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
39 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
88 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
101 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
83 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
77 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
66 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
81 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
76 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
93 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 ...
30
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
77 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
296 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
79 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.