Two parallel plates have equal and opposite charges. When the space between the plates is evacuated, the electric field between the plates is E~ = 3.20 × 105 N/C. When the space is filled with a dielectric, the electric field is E~ = 2.50 × 105 N/C. What is the dielectric constant of this dielectric?

The dielectric constant of this dielectric is 1.28.      

Explanation:

Given that,

When the space between the plates is evacuated, the electric field between the plates,

When the space is filled with a dielectric, the electric field is,

Let k is the dielectric constant of this dielectric. The electric field gets decreased by a factor of k if a dielectric is inserted between plates. So,

So, the dielectric constant of this dielectric is 1.28. Hence, this is the required solution.

the answer is 12 as i may remember

: )