Current Electricity Charging Discharging Of Capacitors Question 321
Question: Every atom makes one free electron in copper. If 1.1 ampere current is flowing in the wire of copper having 1 mm diameter, then the drift velocity (approx.) will be (Density of copper $ =9\times 10^{3},kg,{{m}^{-3}} $ and atomic weight = 63)
[CPMT 1989]
Options:
A) $ 0.3,mm/\sec $
B) $ 0.1,mm/\sec $
C) $ 0.2,mm/\sec $
D) $ 0.2,cm/\sec $
Show Answer
Answer:
Correct Answer: B
Solution:
Density of $ Cu=9\times 10^{3}kg/m^{3} $ (mass of 1 m3 of Cu) $ 6.0\times 10^{23} $ atoms has a mass $ =63\times 10^{3}kg $ \ Number of electrons per $ m^{3} $ are $ =\frac{6.0\times 10^{23}}{63\times {{10}^{-3}}}\times 9\times 10^{3}=8.5\times 10^{28} $ Now drift velocity $ =v _{d}=\frac{i}{neA} $
$ =\frac{1.1}{8.5\times 10^{28}\times 1.6\times {{10}^{-19}}\times \pi \times {{(0.5\times {{10}^{-3}})}^{2}}} $
$ =0.1\times {{10}^{-3}}m,/sec $
BETA
