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.
Questions tagged [resistivity]
61 questions
18
votes
5 answers
What's a conceptual way to understand ohm-cm?
Resistivity is defined in units of \$\Omega \times \textrm{cm}\$. I don't conceptually understand what is meant by the unit.
If it was \$\Omega / \textrm{cm}\$, that would be easy to understand - a certain number of ohms for every centimeter. How…
elile
- 305
- 2
- 6
17
votes
3 answers
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 bulk resistivity of a rock sample using resistor…
Darcy
- 273
- 2
- 5
12
votes
3 answers
Is the electric field in a wire constant?
If \$V=I\cdot R\$ according to Ohm's Law, that implies that \$\frac{\mathrm dV}{ \mathrm dx} = \frac{I \rho}A\$ across an infinitesimal length of conductor, which is constant at all points along the conductor since the current, resistivity, and area…
Ryan
- 149
- 1
- 5
8
votes
4 answers
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 overall color, but have colored patches that may…
Always Confused
- 1,591
- 6
- 25
- 49
6
votes
2 answers
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. Assume the filament is 2.0 cm long, how thick is then…
Peatherfed
- 163
- 2
5
votes
4 answers
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 gives a range of \$1.3\cdot 10^{16}\$ to \$3.3\cdot…
Phil Frost
- 56,804
- 17
- 141
- 262
5
votes
3 answers
Why does increasing altitude (low air pressure) results in lower resistivity/ breakdown voltage?
I got this question because the creepage and clearance distances need to be adjusted for altitude. The higher the altitude, the higher the distances should be. It seems to me however that the contrary is true. What I mean is that we can tolerate…
HatimB
- 826
- 5
- 15
5
votes
3 answers
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 voltage drop. We can't change the size of the…
dthor
- 153
- 5
3
votes
2 answers
How can I make a huge ceramic chip resistor?
I'm an EE, not a physicist or chemist, so please forgive if this question is dumb.
I need a resistor that can dissipate many kW for 10 us, followed by > 10 ms off time.
Since the duty cycle is ~0.1%, I could use a wirewound rated for > 100 W, but…
James Strieter
- 373
- 1
- 6
3
votes
3 answers
How to test an anti-static mat that says \$10^7 \sim 10^9 \Omega\$ surface resistance
I just bought a well-made mat that says surface resistivity is 107 ~ 109 Ω.
The multimeters on the market test up to like 20 MΩ.
If I buy a multimeter to test it:
If it displays infinite, I won’t know if it’s just because it’s between 20 MΩ and 1…
Egoless
- 67
- 6
3
votes
1 answer
Which temperature sensitive material would be a good choice for temperature measurement from 4K to 300K?
I am building a thermometer for a cryostat which operates at low temperatures (until 4 kelvin).
I would like to know the temperature of some parts in my cryostat during the cooling (so from 300 K to 4 K). The idea is to send a small current (in…
Nicolas Schmid
- 133
- 5
3
votes
4 answers
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 be a weighted average of the two values of each…
athedcha
- 175
- 2
- 11
2
votes
2 answers
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 for simple device, which has parallel wires in a…
Roman Susi
- 985
- 3
- 13
- 30
2
votes
1 answer
How good of a conductor is laser-induced graphene from Kapton tape (polyimide)?
I had intentions of making a DC electromagnet using laser-induced graphene (LIG), where the graphene will be used as a flexible electromagnetic coil. Something like those 24V electromagnets you can find online. But I had a concerns on the quality of…
Fulano
- 182
- 7
2
votes
5 answers
High precision resistance meter
I'm designing a high precision resistance meter, which will measure the change of resistance of a given remote resistor, which is not placed on the circuit PCB, against temperature.
I want to do this in the easiest possible way, while also achieving…
Francesco
- 1,005
- 1
- 13
- 31