We didn't go over any fundamental concepts about HOW any of these things work, we just started talking about capacitance, and peak-to-peak voltage. I don't even understand how a voltage source that switches polarity produces a sine wave through time. Why are we even talking about "through time" suddenly? How does the voltage alternate in polarity?
We also talked about degrees on a circle and radians, I'm just confused :(
Any help is appreciated!
Please don't take this simplistic post as talking down.
I have felt overwhelmed before too.
It is easy to forget "how hard it was" before you knew how to do something.
Do you have any memory of before you could walk?
I vividly remember my very first day of school, looking at that alphabet on a banner above the chalkboard and saying to myself "How will i
ever learn all those letters!" .
Professors sometimes skip over the basics. Forgive them, they know a lot and may have forgot when they didnt.
In the beginning you may find it useful to "Freeze" time in you mind .
A movie is a sequence of stills, and AC is at any given instant DC.
So you can stop time in your mind while you figure things out.
As Mr Sophie said one could make AC by simply switching DC.
In practice it is better to have smoother electric power than a switched square wave and a sinewave was agreed on around a hundred years ago. It's fairly easy to make.
I suggest you take a few minutes and a pocket calculator and sheet of graph paper, and plot a graph of volts versus time
VOLTS = 1.414*sin(2 * pi * 60 * time) for time increment of 1.388889 milliseconds (that's 1/720 second)
from time = zero to 16.66667 miliseconds
I suppose you could do it in excel or something, but myself i took one look at xcel and said "How will i
ever learn all those commands?" and stuck with my slide rule.
If you do it by computer, make a column for what's inside those parentheses following 'sin'.
now you have drawn one cycle of a one volt RMS 60 cycle sine wave voltage.
And you have shown your brain how to freeze time.
And if you paid attention to the argument of sin, what's inside the parens, you notice it went from zero to 360 which is # of degrees in a circle.
So 'talking in circles' is a handy way to deal with sinewaves no pun intended (well not much of one)
Note with time increment selected we hit every thirty degrees.
It'll be handy in AC circuits to know sin of every thirty degrees, and 45 too..
Now, you also asked "Why are we even talking about "through time" suddenly?"
Because Tesla and Steinmetz realized around 1900 that if electic industry stayed with direct current there could never be long distance transmission of power.
So they came up with the transformer which requires alternating current,
and the "alternator" to produce it.
AC varies with time, DC does not.
Had we stuck with DC time would be not be so much involved.
But you are exactly where i was that first day of school.
It's not hard to learn this stuff, it's just hard to believe you can. At first.
Admit these ideas. (
Admit in sense of open and allow to enter.)
You'll do fine.
again, no offense intended , just an encouraging word.
old jim
)
As the ghostly digit floated near and far in its tube, they gave the appearance of being alive.
