CBSE · Class 12 · Physics · Electric Charges and FieldsHow many electrons must be removed from a neutral metallic sphere so that it acquires a positive charge of $1.6 \times 10^{-7}\text{ C}$?

According to the principle of quantization of electric charge, $q = n e$, where $q$ is the total positive charge required, $n$ is the number of electrons to be removed, and $e$ is the magnitude of charge on an electron ($1.6 \times 10^{-19}\text{ C}$). Substituting values: $n = \frac{q}{e} = \frac{1.6 \times 10^{-7}\text{ C}}{1.6 \times 10^{-19}\text{ C}} = 10^{12}$ electrons. Thus, $10^{12}$ electrons must be removed.