NEET-XII-Physics
32: Electric Current in Conductors
- #9What length of a copper wire of cross-sectional area 0.01 mm2 will be needed to prepare a resistance of 1 kΩ? Resistivity of copper = 1.7 × 10-8 ΩmAns : Given:
Resistivity of copper, ρcu = 1.7 × 10-8 Ωm
Area of cross-section, A = 0.01 mm2 = 0.01 × 10-6 m2
Required resistance, R = 1 kΩ = 103 Ω
Let l be the required length of the copper wire.
We know:
`` R=\frac{\rho l}{A}``
`` \Rightarrow l=\frac{RA}{{\rho }_{\,\mathrm{\,cu\,}}}``
`` \Rightarrow l=\frac{{10}^{3}\times 0.01\times {10}^{-6}}{1.7\times {10}^{-8}}``
`` \therefore l=0.58\times {10}^{3}\,\mathrm{\,m\,}=0.6\,\mathrm{\,km\,}``
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