Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [resistivity]

A direct measure of how resistive a material is with higher numerical values meaning that the material is more resistive. It is the inverse of conductivity. The units of resistivity are \$ \Omega* m \$ or \$ \Omega* cm \$ (in the semiconductor industry) - not to be confused with resistance that is similar but does not have units of length associated with it.

0
votes
2answers
34 views

High temperature electrical heater

I've been trying to put together a relatively simple electrical circuit to heat an electrode to 750 degrees celsius. In theory, is it simplest to persist with using several car batteries (not those to ...
0
votes
0answers
34 views

voltage amperage ratio for resistive heating of glass [closed]

I am planning to introduce electric heating/boosting in my glass melting furnace. The present temperature of the glass is around 1200 deg C and I need to raise it up to 1300 deg C. I am trying to get ...
0
votes
1answer
36 views

How does capacitive sensing relate to the resistance of the object entering the magnetic field? [closed]

Example: Setting up a capacitive area and dropping resistors of different sizes into the field, how do they affect the field differently? Are several resistors accumulative? Would i be able to tell ...
0
votes
2answers
74 views

Exactly what type of resistor is being referred to in this diagram?

I'm trying to control an RGB LED strip using a NodeMCU. I have been following the guide linked here. However, the diagram included in the diagram is rather unclear, especially for someone like myself ...
0
votes
0answers
388 views

Thermal resistance of a wire of copper

I was reading a book about thermal heat conduction and resistance, when I found the next example: Try to calculate the temperature of a 4-in(0.1m) piece of #12 copper wire at the end that is being ...
0
votes
1answer
41 views

Resistivity of Ferromagnetic Substance

How does the resistivity of a ferromagnetic material change as the material is being magnetized (magnetic domains aligned)?
-2
votes
1answer
38 views

How to calculate size of metal plate for a specified current?

So I'm looking at running a plate from the terminal of a battery (26650) and I'm trying to calculate the width of the plate needed given a certain thickness and length as well as a specified current. ...
0
votes
1answer
3k views

Nichrome wire gauge calculation

I know what battery I wish to use (3.7 V 140 mAh which I can swap for larger mAh battery) I know what length of wire (3.5 inches or 7 inches depending on which ever would work better) I know what ...
13
votes
2answers
1k views

How do you determine the effective resistance of a finite grid of resistors?

Disclaimer: I am a geophysicist with limited electrical engineering background. I am not sure if this problem is incredibly easy, incredibly complex, or completely nonsensical. My goal: Determine the ...
0
votes
2answers
172 views

Are values of resistivity independent of the cross-section and length of the resistor?

I was reading resistivity values for different materials on the wikipedia page. They report the values for standard temperature, but they give no information about the cross-section or length of the ...
0
votes
1answer
301 views

I am trying to make a electro magnet. I bought a coil of enamel copper wire from Ebay. How do I determine its resistance?

I didn't even know you need AWG rating to get a coil's resistance. But this is may sound naive, can I use the physics formula: $$R=\rho\frac{L}{A}$$. \$\rho\$ is resistivity of copper, which I looked ...
3
votes
4answers
980 views

Electrical resistance of two conductors of equal surface area in contact with another?

Resistance of a wire can be determined by the formula R = resistivity*(length/area). What if you have a wire composed of two parallel metals that are in contact with one another? Will the resistivity ...
-3
votes
1answer
96 views

Voltage drop remaining voltage [duplicate]

According to here the resistance drops liniar along the path. In scenario 1 at the start of R1 the resistance the current encounters is 100\$\Omega\$ and at the ...
1
vote
1answer
71 views

Computing the electric potential generated by a current density across media with different conductivities

Model: a right cylinder composed three layers of conductive media. The is a disk of unit charge density in the center of the cylinder. The disk radius is equal to the cylinder radius. The outer layers ...
0
votes
1answer
57 views

MOSFET resistor, difference with no gate or gate at 0V

While measuring a MOSFET resistivity without a gate voltage I have observed that the resistivity obtained for a gate voltage at 0V is 20 times higher than the resistivity observed when there is no ...
0
votes
1answer
384 views

Incandescent bulb for 220V vs 110V and difference of their resistance?

I know that 40Watt,110V incandescent bulb has about 302 ohm resistance of tungsten filament (which is metal and of course have low resistivity) comparing it to 40Watt, 220V bulb which has about 1200 ...
-2
votes
1answer
149 views

Resistance and Resistivity [closed]

How do I calculate the radius of a copper wire dissipating heat of 100mW given that the volume of the conductor is 20mm^3 and is carrying a current of 40nA. Resistivity of copper is 0.0000172.
8
votes
4answers
2k views

What is the identity of this shiny insulator?

fig: Shiny layer I've seen many times, on metallic objects, a kind of insulator layer is given (I've tested its resistance with multimeter and it shows infinite ohms). The layer is greenish-gold in ...
0
votes
1answer
1k views

Is there an internal resistivity in buzzers?

I would like to know if there is an internal resistance in buzzers, and if yes, what could be the internal resistance for a cheap buzzer that can go up to 12V. Thank you
2
votes
1answer
45 views

High Temperature Conductor in Air

I am trying to determine what the best material is for a high temperature conductor. It is for distributing power inside a furnace. I need to run at around 1000 celsius (the furnace is hotter but this ...
0
votes
2answers
1k 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* ...
1
vote
2answers
874 views

nichrome alternatives

I am repairing an AVO multiminor Mk 4 which was in a sort circuit across a car battery while in the 1 amp measuring position. circuit diagram here an obvious casualty was the 0.25 ohm resistance R1 ...
5
votes
3answers
531 views

Given metal dimensions and material, is it possible to determine the maximum current that the structure can handle? [semiconductor processing]

I have a linewidth structure that has very low resistance. I want to know the maximum current that this structure can handle. Since the resistance of the metal is so low, it's hard to measure the ...
1
vote
1answer
380 views

Minimum electrical resistivity of contact material for human protection from lightning

The context of the question is camping and sleeping outdoors in the unprotected elements. If you’re sleeping in a tent close to the ground, and lightning directly strikes your tent or the vicinity ...
0
votes
3answers
158 views

Why are the Resistance/Resistivity Equations Formulated as they are?

The equation for temperature dependence on resistivity: $$ \rho(dT) = \rho(0)(1+\alpha dT) $$ where \$dT\$ is change in temperature from some reference and \$rho\$ is resistivity. This leads to ...
5
votes
4answers
7k views

Can the resistance between two points in air be calculated? How?

If I have just a battery, the terminals are separated by air, a very good insulator. We can say, practically, that no current flows. However, air has a very large, but finite resistivity. Wikipedia ...
-1
votes
2answers
2k views

Wire resistivity

Could you please shed some light on wire resistivity calculations for me.... for example if you have a wire length at 100m with a diameter of 10mm measured at 0.25 ohms.(what material is 0.25?? I can ...
2
votes
2answers
526 views

Schematics for device, which reacts to water?

After failed attempt to combine a resistive wetness sensor with a multivibrator ( How to trigger multivibrator (or similar) from collector? ), I'd like ask a direct question. What could be schematics ...
6
votes
2answers
347 views

Working out thickness of a copper wire

This was one of the questions for the repetition paper before the test. "A lit light bulb has a resistance of 1320 Ω. It uses tungsten as a filament, and when hot, has a resistivity of 0.92 µΩm. ...