iran-konkur 2017 Q182

iran-konkur · Other · konkur-riazi_1396_specialized Not Maths
182. Two copper and aluminum wires of equal length, at a certain temperature, have equal electrical resistance. If the densities of copper and aluminum are respectively $9\,\dfrac{\text{g}}{\text{cm}^3}$ and $2.7\,\dfrac{\text{g}}{\text{cm}^3}$, and the specific resistance of copper is $\dfrac{1}{2}$ times the specific resistance of aluminum, how many times is the mass of the aluminum wire compared to the copper wire?
  • [(1)] $\dfrac{3}{5}$
  • [(2)] $\dfrac{4}{5}$
  • [(3)] $\dfrac{5}{4}$
  • [(4)] $\dfrac{5}{3}$

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\textbf{182.} Two copper and aluminum wires of equal length, at a certain temperature, have equal electrical resistance. If the densities of copper and aluminum are respectively $9\,\dfrac{\text{g}}{\text{cm}^3}$ and $2.7\,\dfrac{\text{g}}{\text{cm}^3}$, and the specific resistance of copper is $\dfrac{1}{2}$ times the specific resistance of aluminum, how many times is the mass of the aluminum wire compared to the copper wire?

\begin{itemize}
    \item[(1)] $\dfrac{3}{5}$
    \item[(2)] $\dfrac{4}{5}$
    \item[(3)] $\dfrac{5}{4}$
    \item[(4)] $\dfrac{5}{3}$
\end{itemize}

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