Maths

[skystorm]

Hi all back on night shift
A conductor has across-sectional area of 20mm2, a lenght of 48m and is made of material with resistivity of 0.02 u ohms m .Its resistance is

 

[brizospark]

please elaborate on uohmsm

 

[i=p/u]

0.02 x 20 x 48

 

[telectrix]

please elaborate on uohmsm

think it's micro ohms/ sq.m. /m.

 

[daiplayer]

(0.02 x 20) x 48 = 19.2 uohm ....?

 

[telectrix]

that's how i read it. but hat's off to I=P/U who got there 1st.

 

[topquark]

that's how i read it. but hat's off to I=P/U who got there 1st.

Yeah, but he didn't put any units on his missing answer

 

[skystorm]

20 x 48 /0.02 = 48.000 or 0.02 x 48 / 20= 0.048

 

[daiplayer]

20 x 48 /0.02 = 48.000 or 0.02 x 48 / 20= 0.048

agreed.....R = pL/a

R = 0.02 x 48000 / 20 ................ p is in mm...so length needs to be in mm?? not sure
R = 48 uohm

 

[telectrix]

i got it wrong, i think.... reminder. don't try calculations after 5 pints.

 

[Richard Burns]

R is resistance in ohms, rho is resistivity Ohm m , l = length in m, A = csa in m[SUP]2[/SUP]
Calculation is R= rho l/A

You have resistivity in microohm m so divide by 1,000,000
You have area in mm2 so divide by 1,000,000
length is in m

R= (rho/1,000,000 (*l))/(A/1,000,000)
rearrange a bit and the millions cancel out so R= rho(in microohoms)* l (in m) / A (in mm2)

Therefore R = 0.02*48 / 20 = 0.048 ohms

perhaps; similar situation to tel!

 

[MarkieSparkie]

Agreed 48 mOhms.

 

[i=p/u]

teletrix you know im going to be a star in the electrical world, going to chase walls today and the boss wont hire wall chaser and said use a kango with chisel just, any tips as i havent done this before

 

[i=p/u]

i was close tho

 

[telectrix]

teletrix you know im going to be a star in the electrical world, going to chase walls today and the boss wont hire wall chaser and said use a kango with chisel just, any tips as i havent done this before

try and avoid waste pipes.