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1R
Wire’s cross section doubled means its cross section area is doubled.
Resistance = (specific resistance ) X (length) / (Area)
Hence, if length and cross section area both doubled, resistance will remain same i.e inchanged.
lets say length is L and cros section is A = pi * r ^2
Resistance, R = (roh * L)/ (pi * r^2)
if the length and cross section both are doubled then the resistance is
R2 = (roh *2L)/ (pi*4r^2)
Now R2/R = [(roh *2L)/ (pi*4r^2)] / [(roh * L)/ (pi * r^2)]
then R2 = R /2
so, the resistance will be half of previous.