Two wires $A$ and $B$ are made up of the same material and have the same mass. Wire A has radius of $2.0 \mathrm{~mm}$ and wire $B$ has radius of $4.0 \mathrm{~mm}$. The resistance of wire B is $2 \Omega$. The resistance of wire $\mathrm{A}$ is_______. $\Omega$.
A$29$
B$30$
C$31$
D$32$
JEE MAIN 2024, Diffcult
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D$32$
d $\because \mathrm{R}=\frac{\rho \ell}{A}=\frac{\rho \mathrm{V}}{\mathrm{A}^2}$
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