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Q15PE
Expert-verifiedUsing the results of the above example on Example 20.3, find the drift velocity in a copper wire of twice the diameter and carrying 20.0 A.
The drift velocity in the copper wire is \[1.08 \times {10^{ - 4}}\;{\rm{m/s}}\].
The given data can be listed below as:
The drift velocity is illustrated as the average velocity attained by a particle because of the involvement of an electric field. The drift velocity significantly contributes to the current’s change in an electric field.
From the example 20.3, the number of copper atoms can be gathered that is\(n = 8.342 \times {10^{28}}\;{{\rm{m}}^{{\rm{ - 3}}}}\) .
The equation of the magnitude of the current is expressed as:
\[{v_d} = \frac{I}{{nq\left( {\pi {{\left( {\frac{d}{2}} \right)}^2}} \right)}}\]
Here, \(I\)is the magnitude of current, \({v_d}\) is the drift velocity, \[n\] is the number of the copper atoms, \[q\] is the charge of one electron and \[d\] is the diameter of the copper wire.
Substitute the values in the above equation.
\[\begin{aligned}{v_d} = \frac{{20.0\;{\rm{A}}}}{{\left( {8.342 \times {{10}^{28}}\;{{\rm{m}}^{{\rm{ - 3}}}}} \right)\left( {1.6 \times {{10}^{ - 19}}\;{\rm{C}}} \right)\left( {\left( {3.14} \right){{\left( {\frac{{{\rm{4}}{\rm{.106 \times 1}}{{\rm{0}}^{{\rm{ - 3}}}}\;{\rm{m}}}}{2}} \right)}^2}} \right)}}\\ = \frac{{20.0\;{\rm{A}}}}{{\left( {1.33 \times {{10}^{10}}\;{\rm{C}} \cdot {{\rm{m}}^{{\rm{ - 3}}}}} \right)\left( {\left( {3.14} \right){{\left( {{\rm{2}}{\rm{.106 \times 1}}{{\rm{0}}^{{\rm{ - 3}}}}\;{\rm{m}}} \right)}^2}} \right)}}\\ = \frac{{20.0\;{\rm{A}}}}{{\left( {1.33 \times {{10}^{10}}\;{\rm{C}} \cdot {{\rm{m}}^{{\rm{ - 3}}}}} \right)\left( {\left( {3.14} \right)\left( {{\rm{4}}{\rm{.4 \times 1}}{{\rm{0}}^{{\rm{ - 6}}}}\;{{\rm{m}}^2}} \right)} \right)}}\\ = \frac{{20.0\;{\rm{A}}}}{{\left( {1.33 \times {{10}^{10}}\;{\rm{C}} \cdot {{\rm{m}}^{{\rm{ - 3}}}}} \right)\left( {{\rm{1}}{\rm{.39 \times 1}}{{\rm{0}}^{{\rm{ - 5}}}}\;{{\rm{m}}^2}} \right)}}\end{aligned}\]
Hence, further as:
\[\begin{aligned}{v_d} = \frac{{20.0\;{\rm{A}}}}{{\left( {184870\;{\rm{C}} \cdot {{\rm{m}}^{{\rm{ - 1}}}}} \right)}}\\ = 1.08 \times {10^{ - 4}}\;{\rm{A}} \cdot {\rm{m/C}}\\ = 1.08 \times {10^{ - 4}}\;{\rm{A}} \cdot {\rm{m/C}} \times \frac{{{\rm{1}}\;{\rm{C/s}}}}{{{\rm{1}}\;{\rm{A}}}}\\ = 1.08 \times {10^{ - 4}}\;{\rm{m/s}}\end{aligned}\]
Thus, the drift velocity in the copper wire is \[1.08 \times {10^{ - 4}}\;{\rm{m/s}}\].
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