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Have you changed the units to m for the diameters and length?http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s11_qp_21.pdf
Q1 b(ii)
please solve, showing the calculations
I tried it several times but my answer repeatedly came the same incorrect value
Btw its my way:
R=p*l/A
7.5=p*(1750/1000)/(phi*(0.5*0.38*10^-3)^2)
7.5*phi*(0.5*0.38*10^-3)^2=1.75p
p=7.5*phi*(0.5*0.38*10^-3)^2/1.75
p=4.8604*10^-7 ohm m.-->4.86*10^-7 ohm m
Hope this helps!