# A conducting wire has length l and area of cross-section A. The resistivity of its material is ρ and its wire resistance is R. It is connected in series with another wire of the same dimensions but of a resistivity 2ρ. The net resistance of the combination is

A conducting wire has length l and area of cross-section A. The resistivity of its material is ρ and its wire resistance is R. It is connected in series with another wire of the same dimensions but of a resistivity 2ρ. The net resistance of the combination is

#### SOLUTION

Since the resistivity R is proportional to the resistivity ρ

R = ρL/A

Since all the dimensions are the same

R = ρ

So the resistance of the second wire will become 2R

Resistance in series = R + 2R = 3R

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