Question

An electric field of 2.15×104 V/m exists between the circular plates of a parallel-plate capacitor that has a plate separation of 2.25 mm. What is the potential difference across the capacitor plates?

What plate radius is required if the positively charged plate is to have a charge of 10.5 μC?

Answer 1

Given the electric field
   
And the plate separation is
   
So, the potential difference is
   
  

The electric field between the plates is given by
     
   
And if the plates are circular then
   
so, we get
  
   
   
Now given the values,
   , , we get the value of the radius of the plates as