How Should Relative Permittivity Be Applied in Electric Field Calculations?

[Jmphysics]

Homework Statement

I've been given a question where I have to find the electric field strength at a point between two charges. Now I understand the mathematics but the question I'm trying to solve says two point charges of value 2C and 3C are position within a medium of relative permittivity 5.5.

My question is when i put my values into the electric field strength equation should this value 5.5 be multiply by the permittivity of free space or be used differently.

Homework Equations

The Attempt at a Solution

I have looked on the internet for the formula but sometimes its written differently and I just want to be one hundred percent confident I'm using this value correctly since I keep finding conflicting information.

 

[Dishsoap]

It is strange that it's worded like that, but my guess is that you multiply the permittivity of free space by 5.5

 

[NascentOxygen]

Hi Jmphysics.

ε_o and ε_r always go around together like a married couple; where you find one it needs the other right alongside.

Some formulae emphasise this by explicitly showing their product ε_oε_r, other formulae denote this product concisely as just ε