What is the difference between ohms and ohms/square??

Question

If you typically measure something in ohms/sq and you get results in the 10^4 - 10^5, what kind of results would you expect in the measurements were in ohms??


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Does one measure surface and one volumetric??

If the substance is of the same material all the way through is the ohms and ohms/sq reading the same and different if the material is multi-layered??

Answer 1

The difference in your measurements would depend on the shape of the object you are measuring.

Ohms/square is a specification of sheet resistance of effectively flat objects.

A real life example of this is a wire trace on a circuit board.
If we are given the sheet resistance of the material in question(ohms/square) we can then calculate the resistance of any trace on the board by measuring its length and width.

For instance lets say I have material with a sheet resistance of 1 ohm/square. I want to find the resistance (ohms) of a trace of this material that is 10mm long and 2mm wide. My resistance is 5ohms (1*10/2)

note: squares = length/width

this calculation can become complex if the item to be measured is not rectangular

Answer 2

My best answer at this point is that you should rewrite your question so that it is an intelligible question. What do you mean, ohms/sq???? ohms^2? that would be ohms*ohms.
ohms^4 would be ohms*ohms*ohms*ohms, and so forth.

However I think you might be confusing ^2/^5 with scientific notation. This involves writing a very large number, say 1000, as 10^3. You read this as 10*10*10, or 1000.

Answer 3

Resistance decreases with increasing cross sectional area, and increases with the length of the conductor. That is,

Resistance (Ohms)=Resistivity*Length/Area

where resistivity contains the material-specific information.

So Ohms/square meter is the resistance of a certain length of stuff with a cross section of 1 m^2 (assuming SI units).

A different "Ohms/square" comes up in layered materials like perovskites. This is the "sheet resistance" which is the effective resistance per quasi 2-dimensional layer of material. To get the resistance of a chunk of the material in this case you need to figure out how many such effective resistors (in parallel) you would have per unit volume.

Answer 4

Ohm measures resistance. While ohm/square measures resistance per unit area. Resistance can be few ohms (10 ohm) to millions of ohms (Mega ohms). But usually the resistors we use in the labs are in the order of couple of hundred ohms to few killo ohms.