Estimate the average drift speed of conduction electrons in a copper wire of cross sectional area 1 x 10-7 m2, carrying a current of 1.5 A.Assume that each copper atom contributes roughly one conduction electron . The no. of copper atoms per cubic metre is 8.5 x 1028.
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What is the average drift speed of conduction electrons in a copper wire of cross-sectional area 1.0×10–7m21.0×10–7m2 carrying a current of 1.5A1.5A. Assume that each copper atom contributes roughly one conduction electron. The density of copper is 9.0×103kg/m39.0×103kg/m3 , and its atomic mass is 63.5u.63.5u.
(A)1.9mm/s(C)2.9mm/s(b)1.1mm/s(D)2.2mm/s(A)1.9mm/s(b)1.1mm/s(C)2.9mm/s(D)2.2mm/s
jeemain physics current-electricity cbse class12 ch5 electric-current-concepts difficult
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asked Feb 14, 2014 by thanvigandhi_1
edited Sep 4, 2014 by thagee.vedartham
1 Answer
The direction of drift velocity of conduction electrons is opposite to the electric field direction,
i.e., electrons drift in the direction of increasing potential. The drift speedvdvd is given by
vd=(I/neA)vd=(I/neA)
Now e=1.6×10−19C,A=1.0×10−7m2,I=1.5Ae=1.6×10−19C,A=1.0×10−7m2,I=1.5A
The density of conduction electrons, nn is equal to the number of atoms per cubic meter
(assuming one conduction electron per CuCu atom as is reasonable from its valence electron count of one).
A cubic meter of copper has a mass of 9.0×103kg9.0×103kg. Since 6.0×10236.0×1023 copper atoms have a mass of 63.5g,63.5g,
n=6×102363.5n=6×102363.5 ×9×106=8.5×1028×9×106=8.5×1028
on substituting in the formula forvdvd, one gets the final answer as 1.1mm/s
ASKHome >> JEEMAIN and NEET >> Physics >> Class12 >> Current Electricity
What is the average drift speed of conduction electrons in a copper wire of cross-sectional area 1.0×10–7m21.0×10–7m2 carrying a current of 1.5A1.5A. Assume that each copper atom contributes roughly one conduction electron. The density of copper is 9.0×103kg/m39.0×103kg/m3 , and its atomic mass is 63.5u.63.5u.
(A)1.9mm/s(C)2.9mm/s(b)1.1mm/s(D)2.2mm/s(A)1.9mm/s(b)1.1mm/s(C)2.9mm/s(D)2.2mm/s
jeemain physics current-electricity cbse class12 ch5 electric-current-concepts difficult
flag Answer comment
Clay6 Question Share Share
asked Feb 14, 2014 by thanvigandhi_1
edited Sep 4, 2014 by thagee.vedartham
1 Answer
The direction of drift velocity of conduction electrons is opposite to the electric field direction,
i.e., electrons drift in the direction of increasing potential. The drift speedvdvd is given by
vd=(I/neA)vd=(I/neA)
Now e=1.6×10−19C,A=1.0×10−7m2,I=1.5Ae=1.6×10−19C,A=1.0×10−7m2,I=1.5A
The density of conduction electrons, nn is equal to the number of atoms per cubic meter
(assuming one conduction electron per CuCu atom as is reasonable from its valence electron count of one).
A cubic meter of copper has a mass of 9.0×103kg9.0×103kg. Since 6.0×10236.0×1023 copper atoms have a mass of 63.5g,63.5g,
n=6×102363.5n=6×102363.5 ×9×106=8.5×1028×9×106=8.5×1028
on substituting in the formula forvdvd, one gets the final answer as 1.1mm/s
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