Question

The value of charge on the oil droplets experimentally observed were $-1.6\times {10}^{-19}$ and $-4\times {10}^{-19}$ coulomb. The value of the electronic charge, indicated by these results 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

The correct option is D $-0.8\times {10}^{-19}$

The relationship between the charge on the oil drop (q) and the charge on the electron (e) 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' to have integer values, $n=2$ and $n^{\prime }=5$

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