An air-filled capacitor consists of two parallel plates, each with an area of A , separated by a distance d . A V potential difference is applied to these plates. What is the magnitude of the electric field between the plates

  E = V / d

Explanation:

In a charged capacitor an electric field is established that goes from the positive to the negative plate, this field is constant,

the potential difference is

           D = E d

in this case they do not give the difference in potential V and the distance between the plates d

           E = V / d

heat the gas and measure the pressure