Current Electricity Charging Discharging Of Capacitors Question 404

Question: There is a current of 40 ampere in a wire of $ {{10}^{-6}},m^{2} $ area of cross-section. If the number of free electron per $ m^{3} $ is $ 10^{29} $ , then the drift velocity will be

[Pb. PMT 2001]

Options:

A) $ 1.25\times ~10^{3}m/s $

B) $ 2.50\text{ }\times ~{{10}^{-3}}m/s $

C) $ 25.0\text{ }\times ~{{10}^{-3}}m/s $

D) $ 250\text{ }\times ~{{10}^{-3}}m/s $

Show Answer

Answer:

Correct Answer: B

Solution:

$ V _{d}=\frac{i}{neA}=\frac{40}{10^{29}\times {{10}^{-6}}\times 1.6\times {{10}^{-19}}} $ = $ 2.5\times {{10}^{-3}}m/sec $ .