# An oil drop has $8.01\times10^{-19}$ C charge. Calculate the number of electrons in this drop.

$(a)\;2\qquad(b)\;3\qquad(c)\;4\qquad(d)\;5$

Charge on oil drop = $8.01\times10^{-19}$
$\because 1.602 \times 10^{-19}$ is charge on one electron
$\therefore 8.01\times10^{-19}$ charge on = $\large\frac{ 8.01\times10^{-19} } {1.602 \times 10^{-19} } = 5$ electrons
Hence answer is (d)
answered Jan 23, 2014
edited Mar 21, 2014