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  • Can someone help me with this, A copper wire of diameter 1.02 mm carries a current of 1.7 amp. Find the drift velocity (vd) of electrons in the wire. Given n, number density of electrons in copper = 8.5 *1028 m3

A copper wire of diameter 1.02 mm carries a current of 1.7 amp.  Find the drift velocity (vd) of electrons in the wire. 

Given n, number density of electrons in copper  = 8.5 *1028 /m3

  • Option 1)

    1.75 mm/sec

  • Option 2)

    1.25 mm/sec

  • Option 3)

    2.5 mm/sec

  • Option 4)

    1.5 mm/sec

 

Answers (1)

best_answer

As we learnt

 

Drift velocity -

 

v_{d}=\frac{I}{neA}=\frac{J}{ne}=\frac{\sigma E}{ne}

- wherein

\sigma=\frac{1}{\rho}\rightarrow Relation

J=\frac{I}{A}\rightarrow Relation

E=\frac{V}{l}\rightarrow Relation

 

 

 

 

I = 1.7 A
J = current density
= \frac{I}{{\pi {r^2}}} = \frac{{1.7}}{{\pi \times {{(0.51 \times {{10}^{ - 3}})}^2}}}$
= nevd
= 8.5 ´ 1028 ´ (1.6 ´ 10-19 ) ´ vd
         vd = \frac{{1.7}}{{\pi \times {{(0.51 \times {{10}^{ - 3}})}^2} \times 8.5 \times {{10}^{28}} \times 1.6 \times {{10}^{ - 19}}}}$
 = 1.5 ´ 10-3 m/sec. = 1.5 mm/sec.


Option 1)

1.75 mm/sec

Option 2)

1.25 mm/sec

Option 3)

2.5 mm/sec

Option 4)

1.5 mm/sec

Posted by

Plabita

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