On Wed, 14 Feb 2007 13:06:33 -0800, "Bob F"
wrote:


"HK" wrote in message
. ..
Thanks everyone. Good information here.

This is a Grade 6 project and I was a little distressed to find that even
the basic concepts of electricity haven't been taught yet they are
supposed
to build a basic circuit and working model.

For instance, my daughter assumed that to power two 6v lights, she needed
a
12v power supply. Yikes.

That's one way to do it.


Is Grade 6 too early to teach Ohm's Law? Should they be learning to hook
up
basic circuits without learning Ohm's Law and the concepts of voltage,
current and resistance?

So teach her ohm's law.


Some of this stuff is coming back to me. Am I correct in assuming that
the
problem with wiring the lights in series is there is too much cumulative
resistance at the far end of the circuit to light the lights?

There is no "far end" of a circuit unless you have long small
wires creating resistance.

And none at all with SERIES circuit.


FYI, we're building a small airboat. There are four 3v LED lights powered
by 2 "C" batteries and a single 6v motor powered by 4 "C" batteries.

"3v LED" suggests LEDs with built in resisters. Remember LEDs
are polarized - if you connect them backwards, they won't light.
2 3v LEDs in series should work fine off of 6V. Do that twice for
4 bulbs.


Any suggestions on a fun followup project that will help both of us learn
more electricity concepts?

A crystal radio?
http://sci-toys.com/scitoys/scitoys/...ade_radio.html

Bob


--
Mark Lloyd
http://notstupid.laughingsquid.com

"Unlike biological evolution. 'intelligent design' is
not a genuine scientific theory and, therefore, has
no place in the curriculum of our nation's public
school classes." -- Ted Kennedy