Physics (AS & A Level) · Oct / Nov 2016 · Paper 12 · Question 31

An oil drop has mass m and charge q. The drop is held stationary in an electric field between two parallel horizontal plates, distance d apart, as shown. The potential difference between the plates is V and the acceleration of free fall is g. What is the charge-to-mass ratio q/m of the oil drop?

1. Agd/V
2. BV/(dg)
3. CgV/d
4. Dd/(Vg)

As printed in the paper