Resistance Level 2 - HELP NEEDED!!

[james1985]

hey,

I am currently completing City & Guilds level 2 and stumbled across the below questions and scratching my head...

1. Electric Fire element has a length of 10m, a cross section area of 0.5mm2 and resistance of 50 ohms - calculate resistivity of material used.

Thanks

 

[davesparks]

No Rho= LxA/resistance, watch out for the csa part, you will need to find the sq root of 0.5

CSA is area, the square root of it will give the length of one side of a square with that area.
The formula for resistivity is:
Rho=R*L/A

 

[james1985]

Dave your a legend, can you break it down so I can see the full calculation....

 

[Pete999]

CSA is area, the square root of it will give the length of one side of a square with that area.

So a csa of 2,5mm2 is ?

Dave your a legend, can you break it down so I can see the full calculation....

I had better stay out Dave has it covered.

 

[telectrix]

So a csa of 2,5mm2 is ?

.

rthe csa of 2.5mm is 2.5sq. mm.

 

[james1985]

Ok so am incorrect in saying the answer is 2.5?

 

[Pete999]

Ok so am incorrect in saying the answer is 2.5?

Think so yes, just thinking I used to be good at this sort of thing, age certainly take it's toll on the memory. Hang on til Dave gets back don't want to add to the confusion.

 

[telectrix]

p = (R x L)/ A

 

[The Ghost]

Its fairly difficult to write the formula and/or a worked example so here is one. Hope it helps. It is simple but you need a sci. calculator.

 

[telectrix]

or here:
Resistance and Resistivity - http://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html

bear in mind that in that example, csa is in sq.cm.

 

[The Ghost]

Sorry it's sideways but you can download it and turn it upright

 

[james1985]

Thanks once again gents, certainly saved me a massive head ache