Part A Constants An electric field is established by applying a potential differ
ID: 1870609 • Letter: P
Question
Part A Constants An electric field is established by applying a potential difference to the plates. It is found that a field c strength Eo will cause the droplet to be suspended motionless. Write an expression for the droplet's charge q. Let g be the acceleration due to gravity Consider an oil droplet of mass m and charge q We want to determine the charge on the droplet in a Millikan-type experiment. We will do this in several steps. Assume, for simplicity, that the charge is positive and that the electric field between the plates points upward Express your answer in terms of the suspending field Eo and the droplet's weight mg View Available Hint(s) Submit Part B The field Eo is easily determined by knowing the spacing between the plates and measuring the potential difference applied to them. The larger problem is to determine the mass of a microscopic droplet. Consider a mass m falling through a viscous medium in which there is a retarding or drag force. For very small particles, the retarding force is given by Fdrag-bu, where b is a constant and v is the droplet's speed. The negative sign tells us that the drag force vector points upward whe the droplet is falling. A falling droplet quickly reaches a constant speed, called the terminal speed Write an expression for the terminal speed vterm Express your answer in terms of m, , and bExplanation / Answer
A)
q = charge on droplet
m = mass of droplet
Fe = force due to electric field on the droplet = qEo
the electric force in upward direction balances the weight in down direction
hence
Fe = mg
qEo = mg
q = mg/Eo