Electrostatics Question 700
Question: The electric field intensity just sufficient to balance the earth?s gravitational attraction on an electron will be: (given mass and charge of an electron respectively are $ 9.1\times {{10}^{-31}}kg $ and $ 1.6\times {{10}^{-19}}C. $ )
Options:
A) $ -5.6\times {{10}^{-11}}N/C $
B) $ -4.8\times {{10}^{-15}}N/C $
C) $ -1.6\times {{10}^{-19}}N/C $
D) $ -3.2\times {{10}^{-19}}N/C $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] $ -eE=mg $
$ \vec{E}=-\frac{9.1\times {{10}^{-31}}\times 10}{1.6\times {{10}^{-19}}}=-5.6\times {{10}^{-11}}N/C $
