Formula for resistance (2 Viewers)

[velox]

what is the formula for calculating the resistance of a particular metal at different temperatures?

 

[lucky]

formula for reisitance of a metal at different temps ?? dun fink there is sucha formula. well.. probably there is.. but i dun fink its in course..

just remember... V = IR and i dunno if u need this one but its...

R = r.L/A.... (fink thats the formula).. R = resiatance (ohms) r = resistivity of wateva u are testing (usually given to you) L =length of the thing... A = area of cross section

 

[velox]

You are correct, it isn't in the course, I was just curious. I've read it in a book somewhere, but can't remember where Anyone know?

 

[lucky]

hmm.... fink about it.. the variables would be... some constant K.... Temp in K (T)... Cross area (A) and the length of thing (L)

R prop. to T
R inv. prop. to A
R prop. to L

probably formula would look some like....

R = k.L.T/A.... k = constant...

but k consists of the resistivity of metal and PROBABLY something else...

so..

R = C.r.L.T / A..... where C=constant... (btw.. im just making this bullshit up in my head..)

hope this helps... probably not..

 

[sneaky pete]

R = kL / A

R = Resistance in Ohms
k = A constant for the material, and is called resistivity; unit is ohm-meter.
L = Length in meters
A = Cross-sectional area in meters²

 

[velox]

but thats only at a specific temperature right?

 

[sneaky pete]

To take into account temperature change:

R = R₁(1+α(ΔT))

R₁ = Resistance at 20ºC (or, reference)
α = Temperature coefficient of the material
ΔT = Change in temperature with respect to reference resistance temperature

 

[velox]

oh ok cool, thanks