Physics (AS & A Level) · Oct / Nov 2019 · Paper 12 · Question 10

A positively charged oil droplet falls in air in a uniform electric field that is vertically upwards. The droplet has a constant terminal speed v₀ and the electric field strength is E. The magnitude of the force due to air resistance acting on the droplet is proportional to the speed of the droplet. Which graph shows the variation with E of v₀?

1. AGraph A: v₀ decreasing linearly from a positive value to zero as E increases
2. BGraph B: v₀ decreasing from a positive value towards zero as E increases
3. CGraph C: v₀ decreasing from a positive value towards a non-zero constant as E increases
4. DGraph D: v₀ constant as E increases

As printed in the paper