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 $1.6\times {10}^{-19}C$)

• 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. $-3.2\times {10}^{-11}N/C$

Answer 1

Answer: (A)

$-5.6\times {10}^{-11}N/C$

$-eE=mg$
$\overrightarrow{E}=-\frac{9.1\times {10}^{-31}\times 10}{1.6\times {10}^{-19}}=-5.6\times {10}^{-11}N/C$