# In Gauss's law, why do we use an infinte long wire or long plane to calculate electric field intensity?

In the NCERT textbook of class 12, in the section on applications of Gauss's law, there are three applications. The first application is to calculate the electric field intensity around an infinitely long wire of uniform charge, and the second application is to calculate the electric field intensity around an infinitely large plane sheet of uniform charge. Why these applications specifically?

• The answer lies in Symmetry, and please don't use capslock like this, it is the internet equivalent of screaming at someone! – Hritik Narayan Apr 18 '15 at 9:31
• Also, I am not sure what your question is. You use Gauss Law to calculate electric field due to an infinitely long wire or plane, we don't use an infinite wire to calculate electric field. – Arpan Banerjee Apr 18 '15 at 10:37
• @santiago emphasize much? ;-) In any case, I don't think this is really a homework question; Mohit isn't asking us to solve the problems mentioned, or to check solutions. It appears to be a conceptual question that is just organized in a confusing manner. I'll see if I can clarify it. Mohit, could you please check whether the edit is accurate? – David Z Apr 18 '15 at 11:57
• okay, comment withdrawn – user77400 Apr 18 '15 at 12:14