Question

A vertical electric field of magnitude $4.9 \times 10^{5} \,N / C$ just prevents a water droplet of a mass $0.1 \,g$ from falling. The value of charge on the droplet will be : (Given $g=9.8\,m / s ^{2}$ )

• A. $1.6 \times 10^{-9} C$
• B. $2.0 \times 10^{-9} C$
• C. $3.2 \times 10^{-9} C$
• D. $0.5 \times 10^{-9} C$

Answer 1

Answer: (B)

$Mg = qE$
$\left(0.1 \times 10^{-3}\right)(9.8)$
$=4.9 \times 10^{5} q$
$\frac{2 \times 10^{-4}}{10^{5}}= q$
$q =2 \times 10^{-9} C$