In the early 1900s, Robert Millikan used small charged droplets of oil, suspended in an electric field, to make the first quantitative measurements of the electron’s charge. A 0.71-um-diameter droplet of oil, having a charge of , is suspended in midair between two horizontal plates of a parallel-plate capacitor. The upward electric force on the droplet is exactly balanced by the downward force of gravity. The oil has a density of 860 kg/m^3 , and the capacitor plates are 4.5 mm apart. Part A
What must the potential difference between the plates be to hold the droplet in equilibrium?
Express your answer to two significant figures and include the appropriate units

ΔV=

The potential difference is  

Explanation:

From the question we are told that

   The diameter of the droplet of oil is

    The density of the oil is  

    The distance of separation of the capacitor plate is  

Generally the radius of the droplet is mathematically represented as

=>      

=>      

Generally the mass of  the oil droplet is mathematically represented as

Here  V  is the volume of the oil droplet which is mathematically represented as

So

=>    

Generally the electric force acting on the droplet is mathematically represented as  

Here q is the charge on an electron with value  

This force is equivalent to the weight of the droplet which is mathematically represented as

So

Here E is the electric field which is mathematically represented as

=>    

=>    

=>