Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area 2.5 \times 10^{-7} {\m}^2 carrying a current of 1.8 {\A}. Assume the density of conduction electrons to be 9 \times 10^{28} {\m}^{-3}.

CBSE Class 12 Physics 2014 Outside Delhi Set 2 Paper

Question : 5 of 9

Marks: +1, -0

Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area

2.5 × 10^{-7} {\m}^2

carrying a current of

1.8 {\A}

. Assume the density of conduction electrons to be

9 × 10^{28}

{\m}^{-3}

Solution:

Given:

\;\;

Current

(l)=1.8 {\A}

Charge density

(n)=9 × 10^{28} {\m}^{-3}

Cross-section area

(A)=2.5 × 10^{-7} {\m}^2

Charge of electron

(q)=1.6 × 10^{-19} {\C}

v_d\;=\;{I}/{n A q} .

\;=\;{1.8}/{9 × 10^{28} × 2.5 × 10^{-7} × 1.6 × 10^{-19}}

\;=0.0005 {\m} \/ {\ s}

\;=0.5 {\mm} {\ s}^{-1}

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