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  •  When 5V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is 2.5<img alt="\times" src="https://entrancecorner.oncodecogs.com/gif.latex?%5Ctimes"

 When 5V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is 2.5\times10 -4 ms -1. If the electron  density  in  the  wire is 8\times1028 m -3 , the resistivity of the material is close to :

 

Option: 1

1.6\times 10^{-8}\Omega\: m


Option: 2

1.6\times 10^{-7}\Omega\: m


Option: 3

1.6\times 10^{-6}\Omega\: m


Option: 4

1.6\times 10^{-5}\Omega\: m


Answers (1)

best_answer

\begin{aligned} &I=A n e v_{d}\\ &\Rightarrow \frac{V}{R}=\text { Anev }_{d}\\ &\Rightarrow \frac{V}{\left(\rho \frac{l}{A}\right)}=\text {Anev}_{d}\\ &\Rightarrow \frac{V A}{\rho l}=A n e v_{d}\\ &\Rightarrow \rho=\frac{V}{l n e v_{d}} \end{aligned}

\begin{aligned} &\Rightarrow \rho=\frac{V}{l* n e v_{d}}=\frac{5}{0.1 \times\left(8 \times 10^{28}\right) \times\left(1.6 \times 10^{-19}\right) \times\left(2.5 \times 10^{-4}\right)} \\ &\Rightarrow \rho =1.5625 \times 10^{-5} \Omega m \approx 1.6 \times 10^{-5} \Omega m \end{aligned}

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vishal kumar

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