Re: simimple experiments
- --- In firstname.lastname@example.org, "Tom Schum" <thomasjschum@...> wrote:
>BTW, the easiest way to run this "double the turns" test is to always
> I ran some math last year and found that the statement you made below
> is somewhat more complicated than it seems.
> Suppose you use the same type wire and wind twice as many turns.
> To double the field strength you have to force the same amount of
> current through double the amount of turns, which then requires at
> least twice the voltage, causing the applied power to double. The
> end result is basically that doubling the number of turns gets you
> not as far as you might expect. Even less, doubling the number of
> turns might reduce efficiency because the added turns are longer than
> the original turns on the coil, since they are usually wound over the
> top of the original turns, so their resistance is greater.
use the same length of wire, regardless of turns. Just use a set
amount of wire for all of your tests. Any extra that you don't need
for your coil, just leave as a (possibly large) loop that is in the
circuit but not wound in the coil. Start your tests with the smallest
number of turns you plan to use, then shorten your loop and add that
to the coil for more turns.
This way the wire resistance never significantly varies and you avoid
all the trouble of special adjustments to maintain the same current
flow with different numbers of turns.
And yes, I am aware that the act of stressing the wire as it's added
to the coil very slightly changes its resistance, but that effect is
not significant for basic testing.