two wires of equal diameters of resistivities row1 and row2 and lengths l1 and l2 respectively are joined in series the equivalent resistivity of the combination is

two wires of equal diameters of resistivities row1 and row2 and lengths l1 and l2 respectively are joined in series the equivalent resistivity of the combination is Two o ual d"eters, O!fes'stivitiæ and and lengths h amd a e The equivalent r y of the iS joined in senes

Dear Student,
Since the diameters of both the wires are same, they have same area of cross-section = a (say)
Resistance of 1st wire, R1 = ρ1l1a; Resistance of 2nd wire, R2 = ρ2l2a
If connected in series, R = R1 + R2 = ρ1l1a+ρ2l2aThe total resistance has the length (l1+l2) and area of cross-section=a.Therefore,ρ = Ra(l1+l2) = ρ1l1a+ρ2l2aa(l1+l2) = ρ1l1+ρ2l2(l1+l2) Ans (a)

Regards,

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