A) 7
B) 8
C) 9
D) 10
Correct Answer: D
Solution :
According to figure, it is clear that electrical force is balanced by weight of body, ie, \[qE=mg\] or \[ne\frac{V}{l}=mg\] \[\therefore \] \[n\times 1.6\times {{10}^{-19}}\times \frac{1200}{6\times {{10}^{-3}}}\] \[=3.2\times {{10}^{-14}}\times 10\] or \[n=\frac{3.2\times {{10}^{-13}}\times 6\times {{10}^{-3}}}{1.6\times {{10}^{-19}}\times 1200}\] \[n=10\]You need to login to perform this action.
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