Two wires of same length and thickness having specific resistances 6 Ω cm and 3 Ω cm respectively are connected in parallel. The effective resistivity is ρ Ω cm. The value of ρ, to the nearest integer, is .

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4. Each wire: Rᵢ=(ρᵢ l)/A. In parallel, R=(ρ₁ρ₂)/(ρ₁+ρ₂)l/A=(18)/9l/A=2l/A. The combination is a conductor of length l and area 2A. ρ_eff=(R×2A)/l=4 Ω cm.

Two wires of same length and thickness having specific resistances 6 Ω cm and 3 Ω cm respectively are connected in parallel. The effective resistivity is ρ Ω cm. The value of ρ, to the nearest integer, is ______.

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