When a magnetic body is placed in a uniform magnetic field, there is a demagnetizing magnetic field generated inside the nanoparticle which is opposite to the direction of the applied field. We know that the demagnetizing field is given by Hd= N.Ms where N is the demagnetizing factor. In case of spherical body, N is equal to 1/3. So, will it be the same if we consider a spherical magnetic nanoparticle as the spherical body. I want to model the magnetic field around a magnetic nanoparticle of size around 50nm. Please provide some suggestions and ideas about how to approach the problem.