# Alternating acceleration understanding ?

1. Oct 22, 2011

### khurram usman

alternating acceleration understanding....?

i have a basic understanding of this topic......i understand this thing when it is explained using a closed rectangular circuit in books......it is easy to imagine that in a small closed circuit the curent first flows in one direction then in the other.
but i could not understand how can alternating current reach our homes ....i mean first we say that in one direction and after half a time period it moves in the other....so in a sense it should reach back its starting point.....kindly explain this and improve my understanding
someone told me to view this as a progressive wave/transfer of energy....where energy goes from one maximum to other maximum....but what i dont uinderstand is how and when it changes it direction?
secondly i remeber someone telling me that a AC bulb blinks about 60 times in a minute.....but obviously our eye cant detect that....now if i assume that progressive wave concept which i dont clealy undrstand how is this explained?
thirdly the alternating voltage will cause the current to alternate .....that is its direction and magnitude both change(since its a sine wave)then doesnt this magnitude changing affect the appliances....i mean why dont tube lights and bulbs glow sometimes brightly and sometimes dimly?
please provide me an explanation and a physical interpretation of these concepts

2. Oct 22, 2011

### elegysix

Re: alternating acceleration understanding....?

Think of it like this, me pushing a rod(electrons) into you to supply you with energy (DC), or me pushing and pulling the rod(electrons) to and from you (AC). While I would run out of rod(electrons) eventually by only pushing it to you(DC), this would not happen if I pushed it and pulled it(AC). Instead, I just have to provide the energy in pushing and pulling, and not a supply of electrons. It is the potential in the circuit which is usable energy, and alternating that potential allows you to do work, without having any 'net' flow of electrons.

And yes things like light fixtures running off AC flicker at a frequency of either 60hz or 120hz, i forget which. Its too fast for our eyes to detect, but when you record an old school monitor with an older camera, you will see that it is flickering and doing strange things that we don't notice.