Because insulators are those material which do not conduct electricity even in the applied electric field since insulators have not free electrons.
While dielectric is an insulator that can be polarized by applying electric field.
Explanation:
When a dielectric is placed in an electric field, electric charges do not flow throughout the material (as in case of conductor) but there is only slightly shift of charges from there average equilibrium position which causing dielectric polarization
- +ve charges are displaced towards the direction of electric field.
- -ve charge shifts in opposite direction of electric field.
- This create an internal field that reduces the overall field within the dielectric itself.
- Since in case of dielectrics there are no free charge carriers. So these are capable of storing charge.
clear cut physics📚 