Question

If an electron experiences a force equal to its weight when placed in an electric field, the intensity of the electric field is :
( Mass of electron $=9\times {10}^{-31}kg$ , $g=10m{s}^{-2})$

• A. $5.62\times {10}^{-11}N/C$
• B. $5.62\times {10}^{11}N/C$
• C. $5.62\times {10}^{-9}N/C$
• D. $5.62\times {10}^{9}N/C$

Answer 1

The correct option is A $5.62\times {10}^{-11}N/C$

Weight of $1$ $e^{-}=mg$
$=9\times {10}^{-31}\times 10$
$=9\times {10}^{-30}$
We know force $F=Eq$
$\Rightarrow Eq=9\times {10}^{-30}$

$\Rightarrow E=\frac{9\times {10}^{-30}}{1\cdot 6\times {10}^{-19}}$

$\Rightarrow E=5\cdot 62\times {10}^{-11}N/C.$