Current Electricity Charging Discharging Of Capacitors Question 675
Question: The total momentum of electrons in a straight wire of length 1000m carrying a current of 70A is closest to
Options:
A) $ 40\times {{10}^{-8}}N-\sec $
B) $ 30\times {{10}^{-8}}N-\sec $
C) $ 50\times {{10}^{-8}}N-\sec $
D) $ 70\times {{10}^{-8}}N-\sec $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] No. of electron in the wire $ =nA\ell ,(n={{e}^{-}}\text{density}) $ and momentum $ =n,eA,v _{d}=\frac{\ell m _{e}}{e}=\frac{I,\ell m _{e}}{e} $
$ =\frac{70\times 1000}{1.6\times {{10}^{-19}}}\times 9.1\times {{10}^{-31}}=40\times {{10}^{-8}}N-\sec $
BETA
