1.

The resistivity of iron is\[1\times {{10}^{-7}}\,ohm-m\]. The resistance of a iron wire of particular length and thickness is 1 ohm. If the length and the diameter of wire both are doubled, then the resistivity in \[ohm-m\] will be [CPMT 1983; DPMT 1999]

A. \[1\times {{10}^{-7}}\]
B. \[2\times {{10}^{-7}}\]
C. \[4\times {{10}^{-7}}\]
D. \[8\times {{10}^{-7}}\]
Answer» B. \[2\times {{10}^{-7}}\]


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