A uniform metallic wire carries a current 2 A, when 3.4 V battery is connected across it. The mass of uniform metallic wire is 8.92 $\times$ 10$^{-3}$ kg, density is 8.92 $\times$ 10$^{3}$ kg/m$^3$ and resistivity is 1.7 $\times$ 10$^{-8}~\Omega$-$\mathrm{m}$. The length of wire is :
Solution
$m=8.92 \times 10^{-3} \mathrm{~kg}$
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Density $=8.92 \times 10^{3} \mathrm{~kg} / \mathrm{m}^{3}$
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Volume $=\frac{8.92 \times 10^{-3}}{8.92 \times 10^{3}}=\left(10^{-6}\right) \mathrm{m}^{3}$
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Resistance $=\frac{3.4}{2}=1.7 \Omega=\left(\frac{\rho l}{A}\right)$
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$1.7=\frac{\rho l^{2}}{(A l)}$
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$\Rightarrow 1.7=\frac{1.7 \times 10^{-8} \times l^{2}}{10^{-6}}$
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$l^2=100$
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$l=10 \mathrm{~m}$
About this question
Subject: Physics · Chapter: Current Electricity · Topic: Ohm's Law and Resistance
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