Lychee628
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#1
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#1
http://filestore.aqa.org.uk/subjects...1-QP-JUN15.PDF
7c?
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Joinedup
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#2
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Work out the resistance of 1.0 km of the cable by treating the wires making up the cable as resistances in parallel

do P=V2/R
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Lychee628
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(Original post by Joinedup)
Work out the resistance of 1.0 km of the cable by treating the wires making up the cable as resistances in parallel

do P=V2/R
So do 75^2/(1.1/6)
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Joinedup
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(Original post by Ayaz789)
So do 75^2/(1.1/6)
That's just the 6 aluminium wires... the steel wire should also be included
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Lychee628
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#5
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(Original post by Joinedup)
That's just the 6 aluminium wires... the steel wire should also be included
So its 75^2/(1.1/6)+3.3?
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Joinedup
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(Original post by Ayaz789)
So its 75^2/(1.1/6)+3.3?


should be getting 752/0.17 for 33kW
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Lychee628
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#7
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(Original post by Joinedup)
should be getting 752/0.17 for 33kW
How did you get 0.17 on the bottom?
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Joinedup
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(Original post by Ayaz789)
How did you get 0.17 on the bottom?
1/R=1/R1+1/R2...
so
R=1/(1/1.1+1/1.1+1/1.1+1/1.1+1/1.1+1/1.1+1/3.3)
or
R=1/(6*(1/1.1)+1/3.3)
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Lychee628
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#9
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(Original post by Joinedup)
1/R=1/R1+1/R2...
so
R=1/(1/1.1+1/1.1+1/1.1+1/1.1+1/1.1+1/1.1+1/3.3)
or
R=1/(6*(1/1.1)+1/3.3)
Okay thanks i understand it
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