In a Millikan's oil drop experiment,the charge on an oil drop is calculated to be $6.35 \times 10^{-19} \ C$. The number of excess electrons on the drop is:

When $10^{14}$ electrons are removed from a neutral metal sphere,the charge on the sphere becomes ...... $\mu C$.

$A$ polythene piece rubbed with wool is found to have a negative charge of $3.52 \times 10^{-7} \text{ C}$. What is the number of electrons transferred?

Which experiment was used to determine the quantization of electric charge?

While doing his experiment,Millikan one day observed the following charges on a single drop:
$(i)$ $6.563 \times 10^{-19} \ C$
$(ii)$ $8.204 \times 10^{-19} \ C$
$(iii)$ $11.50 \times 10^{-19} \ C$
$(iv)$ $13.13 \times 10^{-19} \ C$
$(v)$ $16.48 \times 10^{-19} \ C$
$(vi)$ $18.09 \times 10^{-19} \ C$
From this data,the value of the elementary charge $(e)$ was found to be:

How can you charge a metal sphere positively without touching it?