Free vs Bound Charge

D = ε₀ E + P

Free charges sit on the plates. If a dielectric is present, it polarizes and creates bound surface charge. Set susceptibility to zero to remove the material and return to vacuum.

Free surface charge σ_f 50

Susceptibility χ_e 2.0

free charge on plates

bound charge on dielectric

D: free charge only

E: total field

P: polarization