CAPE Physics Unit 2 · 2017 · Paper 1 · Question Q35

In Millikan's oil drop experiment, a charged drop of mass 4 \times 10^{-15}\text{ kg} is suspended between the metal plates by an electric field of strength 4.2 \times 10^4\text{ V}\text{ m}^{-1}. The charge of the drop is

1. (A)2\text{ e}
2. (B)6\text{ e}
3. (C)9\text{ e}
4. (D)10\text{ e}