- Home
- Standard 12
- Physics
11.Dual Nature of Radiation and matter
medium
$n$ Millikan oil drop experiment, a charged drop of mass $1.8 \times {10^{ - 14}}kg $ is stationary between its plates. The distance between its plates is $0.90 cm$ and potential difference is $2.0$ kilo volts. The number of electrons on the drop is
A
$500$
B
$50$
C
$5$
D
$0$
Solution
(c) $QE = mg$
$ \Rightarrow Q = \frac{{mg}}{E}$
$ \Rightarrow n = \frac{{mgd}}{{Ve}}$
$ \Rightarrow n = \frac{{1.8 \times {{10}^{ – 14}} \times 10 \times 0.9 \times {{10}^{ – 2}}}}{{2 \times {{10}^3} \times 1.6 \times {{10}^{ – 19}}}} = 5$
Standard 12
Physics
