(a)[7]
Describe the main ideas behind determining the charge on an oil drop in Millikan’s experiment. A diagram may be included if you want.
(b)[1]
In an experiment to determine the fundamental charge, the charge values on oil drops found by a student were as follows. $3.2 \times 10^{-19}\,\text{C}$; $6.4 \times 10^{-19}\,\text{C}$; $16 \times 10^{-19}\,\text{C}$; $9.7 \times 10^{-19}\,\text{C}$; $12.8 \times 10^{-19}\,\text{C}$; $3.1 \times 10^{-19}\,\text{C}$; $6.3 \times 10^{-19}\,\text{C}$. State the value, to two significant figures, of the fundamental charge suggested by these charge values on oil drops.