Tia Leschke

Now we get into my lack of understanding of physics. Lars wants to know why
you couldn't get a lightbulb burning with a battery and have a battery of
solar panels around it that would keep feeding energy into the original
lightbulb so you could disconnect the battery. I know you can make a solar
panel work with electric light because we tried it once with a little solar
panel kit we got for him. I know it wouldn't work the way he thinks it
would, like you can't really make a perpetual motion machine, but I can't
put my finger on why. I know there's a physics principal that applies, but
I never *got* physics.

Help anyone?
Tia

Nora or Devereaux Cannon

Ummmm because it gets dark??? Really he's asking about
capacitors I think - something that holds the charge while the
sun isn't shining.

Having raised a kid who still at 24 is convinced he WILL invent
perpetual motion (other than his own) and anti gravity and
invisibility... I commend a trip to Goodwill for a number of
things that operate on a simple electric motor (round and round),
along with a subscription to a few mags you find in the shade
tree mechanic's bathroom - Popular Mechanics etc. Mother Earth
News is great, but you want "down and dirty" "what works how" to
capture that budding engineer - as well as to let him teach
himself. If it scares you to think about physics, you'll scare
him trying to do much to help him learn.

Oh also, at a yardsale get one of those "75 electrical
experiments" box kits. I never got a nibble on a new, pristine
ones - but the ones with a few missing wires and unidentifiable
stain on the back were hours of fun.



----- Original Message -----
From: "Tia Leschke" <leschke@...>
To: <[email protected]>
Sent: Monday, February 24, 2003 6:26 PM
Subject: [Unschooling-dotcom] Solar Energy/Perpetual Motion


| Now we get into my lack of understanding of physics. Lars
wants to know why
| you couldn't get a lightbulb burning with a battery and have a
battery of
| solar panels around it that would keep feeding energy into the
original
| lightbulb so you could disconnect the battery. I know you can
make a solar
| panel work with electric light because we tried it once with a
little solar
| panel kit we got for him. I know it wouldn't work the way he
thinks it
| would, like you can't really make a perpetual motion machine,
but I can't
| put my finger on why. I know there's a physics principal that
applies, but
| I never *got* physics.
|
| Help anyone?
| Tia
|
|
| ~~~~ Don't forget! If you change topics, change the subject
line! ~~~~
|
| If you have questions, concerns or problems with this list,
please email the moderator, Joyce Fetteroll
(fetteroll@...), or the list owner, Helen Hegener
(HEM-Editor@...).
|
| To unsubscribe from this group, click on the following link or
address an email to:
| [email protected]
|
| Visit the Unschooling website: http://www.unschooling.com
|
| Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
|
|
|

Tupelo Fogacci

It may light up for a while, but will slowly get dimmer until it does not
light at all. When energy is transferred, some of it is lost. So the
energy required to power a light bulb is greater than the energy emitted as
light. Some of this "lost" energy is expressed as heat. Therefore, the
light cannot create enough energy to power itself continuously. However,
even if the light energy was sufficient when it left the bulb, some of the
energy from the light is lost when it travels to the panel, some is lost
while being absorbed, some is lost traveling through the wires, and so on.
So the energy would not be enough to light the bulb with the same brilliance
once it got back there.

Hope that helps!

Tupelo
Mom to 6yo magic school bus/Bill Nye/general science enthusiast! And a
lurker who has finally decided to start chatting!






----Original Message Follows----
From: Tia Leschke <leschke@...>
Reply-To: [email protected]
To: [email protected]
Subject: [Unschooling-dotcom] Solar Energy/Perpetual Motion
Date: Mon, 24 Feb 2003 16:26:29 -0800

Now we get into my lack of understanding of physics. Lars wants to know why
you couldn't get a lightbulb burning with a battery and have a battery of
solar panels around it that would keep feeding energy into the original
lightbulb so you could disconnect the battery. I know you can make a solar
panel work with electric light because we tried it once with a little solar
panel kit we got for him. I know it wouldn't work the way he thinks it
would, like you can't really make a perpetual motion machine, but I can't
put my finger on why. I know there's a physics principal that applies, but
I never *got* physics.

Help anyone?
Tia



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Fetteroll

on 2/24/03 7:26 PM, Tia Leschke at leschke@... wrote:

> Lars wants to know why
> you couldn't get a lightbulb burning with a battery and have a battery of
> solar panels around it that would keep feeding energy into the original
> lightbulb so you could disconnect the battery.

Well it's confusing because he has some concept that batteries are supplying
something that solar cells aren't. Maybe if you ask him what he thinks is
happening with the light bulb and the battery then you can explain it
better.

You could hook up a light bulb to solar panels and have it light. There
isn't a need for a battery to get it started. You just hook it up. (A rather
bizarre concept, though, converting light to electricity in order to convert
electricity to light ;-)

The lightbulb doesn't know what it's connected to. All it knows is that
there's something pushing enough electricity into it (and supplying an
outlet path for the electricity) to get the filament hot enough to emit
photons.

Maybe he's seeing a difference between the electricity supplied by batteries
and that supplied by solar panels? But they're the same. They are both
objects that convert one form of energy into another form (electricity). A
battery converts chemical energy into electrical energy. Solar panels
convert solar energy into electrical energy. A generator converts mechanical
(wind, moving water, moving pistons) energy into electrical energy.

One difference is a battery has a limited supply of chemical energy. Once
all the chemicals are changed, it can't supply any more electricity. Same
for generators that run off gasoline. Once the energy that's being converted
to electrical energy is gone, so's the electricity. But solar panels and
wind and water power generators *appear* to have an unlimited supply of
energy to convert to electricity. But of course that's not true. If the wind
dies or the sun goes down, the electricity stops just like a battery's.

Joyce

Fetteroll

on 2/24/03 10:48 PM, Tupelo Fogacci at tupelohoney1@... wrote:

> It may light up for a while, but will slowly get dimmer until it does not
> light at all. When energy is transferred, some of it is lost. So the
> energy required to power a light bulb is greater than the energy emitted as
> light. Some of this "lost" energy is expressed as heat. Therefore, the
> light cannot create enough energy to power itself continuously. However,
> even if the light energy was sufficient when it left the bulb, some of the
> energy from the light is lost when it travels to the panel, some is lost
> while being absorbed, some is lost traveling through the wires, and so on.
> So the energy would not be enough to light the bulb with the same brilliance
> once it got back there.
>
> Hope that helps!
>
> Tupelo
> Mom to 6yo magic school bus/Bill Nye/general science enthusiast! And a
> lurker who has finally decided to start chatting!
>
>
>
>
>
>
> ----Original Message Follows----
> From: Tia Leschke <leschke@...>
> Reply-To: [email protected]
> To: [email protected]
> Subject: [Unschooling-dotcom] Solar Energy/Perpetual Motion
> Date: Mon, 24 Feb 2003 16:26:29 -0800
>
> Now we get into my lack of understanding of physics. Lars wants to know why
> you couldn't get a lightbulb burning with a battery and have a battery of
> solar panels around it that would keep feeding energy into the original
> lightbulb so you could disconnect the battery. I know you can make a solar
> panel work with electric light because we tried it once with a little solar
> panel kit we got for him. I know it wouldn't work the way he thinks it
> would, like you can't really make a perpetual motion machine, but I can't
> put my finger on why. I know there's a physics principal that applies, but
> I never *got* physics.
>
> Help anyone?
> Tia
>
>
>
> _________________________________________________________________
> MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*.
> http://join.msn.com/?page=features/virus
>
>
> ~~~~ Don't forget! If you change topics, change the subject line! ~~~~
>
> If you have questions, concerns or problems with this list, please email the
> moderator, Joyce Fetteroll (fetteroll@...), or the list owner, Helen
> Hegener (HEM-Editor@...).
>
> To unsubscribe from this group, click on the following link or address an
> email to:
> [email protected]
>
> Visit the Unschooling website: http://www.unschooling.com
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

Fetteroll

on 2/24/03 10:48 PM, Tupelo Fogacci at tupelohoney1@... wrote:

> However,
> even if the light energy was sufficient when it left the bulb, some of the
> energy from the light is lost when it travels to the panel, some is lost
> while being absorbed, some is lost traveling through the wires, and so on.
> So the energy would not be enough to light the bulb with the same brilliance
> once it got back there.

Oh, now I understand what he was asking! Yikes, boy was I confused ;-)

Yes, what Tupelo said. That's the same with any perpetual motion machine.
Energy doesn't get converted perfectly from one form to another. There's
always some energy that gets converted to something you don't want.

Lots of the energy going into the light bulb is converted to heat to get the
molecules banging around against each other in the filiment to emit photons.
That energy can't be recaptured by a solar panel. Even florescents which can
convert more of the energy into light than incandescents get really hot even
though it doesn't seem like it because the gas is spread out. The molecules
inside are moving very fast.

And that heat loss happens all along the process. Not all of the solar
energy gets converted to electricity because of heat loss. Not all of the
electricity gets to the light bulb because of heat loss. Molecules
vibrating, atoms, electrons banging around.

Joyce

[email protected]

In a message dated 2/25/03 7:04:30 AM, fetteroll@... writes:

<< You could hook up a light bulb to solar panels and have it light. There
isn't a need for a battery to get it started. You just hook it up. (A rather
bizarre concept, though, converting light to electricity in order to convert
electricity to light ;-)
>>

Between Santa Fe and Albuquerque there's a freeway exit with solar powered
lights. It woudln't make sense to have them light up straight across,
because if the sun's shining you don't need the lights! <g>

I had a little Casio solar calculator I just loved. A light bulb was enough
light to get it to work.

I'm impressed that those BIG outside lights work from solar collectors.

Sandra

mary krzyzanowski

We have a solar calculator too. The kids love to play with it and I love
that it doesn't need batteries!
Mary-NY






>From: SandraDodd@...
>Reply-To: [email protected]
>To: [email protected]
>Subject: Re: [Unschooling-dotcom] Solar Energy/Perpetual Motion
>Date: Tue, 25 Feb 2003 11:09:23 EST
>
>
>In a message dated 2/25/03 7:04:30 AM, fetteroll@... writes:
>
><< You could hook up a light bulb to solar panels and have it light. There
>isn't a need for a battery to get it started. You just hook it up. (A
>rather
>bizarre concept, though, converting light to electricity in order to
>convert
>electricity to light ;-)
> >>
>
>Between Santa Fe and Albuquerque there's a freeway exit with solar powered
>lights. It woudln't make sense to have them light up straight across,
>because if the sun's shining you don't need the lights! <g>
>
>I had a little Casio solar calculator I just loved. A light bulb was
>enough
>light to get it to work.
>
>I'm impressed that those BIG outside lights work from solar collectors.
>
>Sandra

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