As we know,
R = ρl/A
where, ρ = resistivity of the material, l is length of material, R is resistance of material and A is cross-sectional area.
According to question, length (l) and resistance of material ® is same for both.
In both cases, what’s varying is the resistivity of copper and manganin.
resistivity of manganin (ρm) = 4.2 × 10-7
resistivity of cupper (ρc) = 1.7 × 10-8
so, ρc < ρm
Hence, thickness depends of cross-sectional area.
Manganin wire is thicker than copper wire.
Thanks! Hope you got it.