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current to keep sensitive
electronics from being overloaded.
If you break open a resistor, you'll
find a pile of graphite. If you have
a digital multimeter, draw a line on
a sheet of paper with a graphite
pencil, and place one probe near There’s an equation for calculating
the end of the line. You can it (called the parallel resistance
measure the change in resistance formula). But the general idea is
along the line with your other that half the current goes through
multimeter probe! each one. So, if you connected
Okay, you can look it up to learn two 100 ohm resistors in parallel,
more about it if you want, but for you would end up with the
now, we’re just going to keep in equivalent of a 50-ohm resistor.
mind that resistors reduce current. The last thing to know about
If you hook up a couple of them in resistors is how to determine their
a circuit called a voltage divider, value (how many ohms they are).
they can reduce voltage too. For whatever reason, instead of
A couple of useful resistor factoids printing numbers on them like
you should know: most other electronic components,
they put colored stripes on them.
Two resistors connected in series So, we compare the stripes to a
add their resistances together. So color code chart, and it tells us how
if I have a 100 ohm resistor and a many ohms a resistor is.
50 ohm resistor and connect them
in series, I’ll get 150 ohms. Most resistors have 4 colored
stripes on them. Here’s what each
one means.
The first band gives the first
digit.
The second band gives the
second digit.
If I connect two resistors in The third band indicates the
parallel, it actually decreases their number of zeros.
total resistance.
The fourth band is used to
show the tolerance of the
resistor
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