Form factor used in transmitting electricity

Thankyou owlwings for your fwwdback but wikipedia is not opening in my browsers when i try to open it says The Connection Was Reset The connection to the server was reset while the page is loading Any good alternative I also search the result on search engine but i don't get any good posting.

I'm sorry that you don't seem to have access to Wikipedia. If you are logging in from a school or college, they may have blocked the URL, otherwise I have no explanation for it. Your question and your use of the term 'form factor' is not very clear and so I can assume that your knowledge is limited. If you are asking why the voltage of household electricity often seems to be 110v or 220v, I don't think there is any clear answer and, in any case, it is not always true (240v has been a standard in the UK, at least, for many years). The voltage at which main power lines operate is chosen to minimise wastage due to transmission losses and there are many factors taken into account, including the resistance of the lines, back EMF (inductance) and capacitance. It would take too long to describe these here (and to list the advantages and disadvantages of high and low voltage lines and the reasons for using alternating current rather than direct current). You are best advised, therefore, to read about it online and to refer to textbooks on the subject because you are bound to come across things you do not understand and will, therefore, have to go back to research those.