susceptibility dielectric material

[jackxxny]

1. The problem statement, all variables and given/known data
I have a linear dielectric material. The electric field in the material is 38% less than a vacuum field with the same external sources. I need to find the susceptibility of the material?

2. Relevant equations

I used
P=\epsilon\chi(vacuum)E
P=\epsilon\chi(material).62E


3. The attempt at a solution
i did the ratio of the 2 and i found

\chi(material)= 1.61

is this correct?

[gabbagabbahey]

i did the ratio of the 2 and i found

\chi(material)= 1.61

is this correct?

I'm not sure what you mean here.. the polarization in vacuum should be zero shouldn't it? What field stays the same when the free charge sources are unchanged? Electric field ? Displacement field? Polarization?