Question

The value of charge on th oil droplets experimentally observed were $-1.6{\times 10}^{-19}$ and $-4\times {10}^{-19}$ coulomb. the value of the electron charge, indicates by these result is:

• A. $1.6{\times 10}^{-19}$
• B. $-2.4{\times 10}^{-19}$
• C. ${-4\times 10}^{-19}$
• D. $-0.8{\times 10}^{-19}$

Answer 1

Answer: (D)

$-0.8{\times 10}^{-19}$

The relationship between the charge on the oil drop $\left(q\right)$ and the charge on the electron $\left(e\right)$ is $q=ne$

Where $n$ is an integer which indicates the number of electrons present on an oil drop.

From the given data, $e=\frac{q}{n}=\frac{-1.6\times {10}^{-19}}{n}=\frac{-4\times {10}^{-19}}{n^{{}^{\prime }}}$

For $n$ and $n^{{}^{\prime }}$ to have integer values, $n=2$ and $n^{{}^{\prime }}=5$

Hence, $e=\frac{q}{n}=\frac{-1.6\times {10}^{-19}}{2}=\frac{-4\times {10}^{-19}}{5}=-0.8\times {10}^{-19}$

$\therefore$ Correct answer is D.