Learning about the ideal physics modelsWatch this thread
1) The thin lens model If we take into account the finite lens thickness, then new quantitative and even qualitative effects can be observed. http://www.eu-journal.org/index.php/...ticle/view/143
2) The paraxial approximation. If we take into account the finite values between optical axis and incident rays, then new quantitative and even qualitative effects can be observed http://www.revistacubanadefisica.org...ew/2020v37p084
3) The model of conductor with fixed cross-section and length We can explore the influence of variable (along the length) cross-section of some conductors on the final results of the rsistance. https://www.scielo.br/j/rbef/a/YmdXR...en&format=html
In all of these cases we employ the de-idealization procedure, that is, construction of extended (or, genaralized) in some manner models. It gives us the possibility to test (probe) initial (limiting) models, to evaluate their applicability limits.