Solar Panel Question

[Chesterton]

What happens if you use one of those mini-solar panels to power a flashlight, then use another one to power another flashlight, and then shine the lights at each other's panels? Would each light continue to power the other light, as if in some kind of perpetual motion? Would that work in theory? In practice?

 

[Nithavela]

What happens if you use one of those mini-solar panels to power a flashlight, then use another one to power another flashlight, and then shine the lights at each other's panels? Would each light continue to power the other light, as if in some kind of perpetual motion? Would that work in theory? In practice?

Solar panels don't turn all the light falling on them into energy, and flashlights don't turn all the energy powering them into light. So no, obviously it wouldn't work.

 

[Chesterton]

Solar panels don't turn all the light falling on them into energy, and flashlights don't turn all the energy powering them into light. So no, obviously it wouldn't work.

I know, but why wouldn't it work with the portion of energy that is getting converted?

 

[Nithavela]

I know, but why wouldn't it work with the portion of energy that is getting converted?

Because very quickly after setting up this device, the energy produced would no longer be sufficient to produce any light at all. If you had a really, really efficient setup, you MIGHT see a couple of seconds of light dimming quickly before it goes out.

That's not "perpetual motion" though. This is just a "troll physics" meme.

 

[Chesterton]

Because very quickly after setting up this device, the energy produced would no longer be sufficient to produce any light at all.

Why?

That's not "perpetual motion" though. This is just a "troll physics" meme.

I didn't know it was a meme. I just saw a video of a guy powering a small fan by shining a flashlight at a panel, so why couldn't you power another light, which in turn powers the first? I'm sure I'm not understanding something, but I don't know what.

 

[The IbanezerScrooge]

Because very quickly after setting up this device, the energy produced would no longer be sufficient to produce any light at all. If you had a really, really efficient setup, you MIGHT see a couple of seconds of light dimming quickly before it goes out.

That's not "perpetual motion" though. This is just a "troll physics" meme.

Kind of like strapping a piece of buttered toast buttered side up to a cat's back. Since buttered toast always lands buttered side down and cats always land on their feet... Voilà! Perpetual motion!

 

[Nithavela]

I didn't know it was a meme.

I just saw a video of a guy powering a small fan by shining a flashlight at a panel, so why couldn't you power another light, which in turn powers the first? I'm sure I'm not understanding something, but I don't know what.

You do understand that when you shine light onto a solar panel, only a small portion is converted into electricity (like, 10-20 percent)?
You also understand that a flashlight only turns a part of the electricity into light, with some of that energy going into heat?

 

[Chesterton]

You do understand that when you shine light onto a solar panel, only a small portion is converted into electricity (like, 10-20 percent)?
You also understand that a flashlight only turns a part of the electricity into light, with some of that energy going into heat?

Yes, I actually just "got it". It clicked in my head just before you posted. Thanks for the answer.

P.S. Guys I didn't know say it would be perpetual motion. My exact words were "as if in some kind of perpetual motion".

 

[Sophrosyne]

The problem is that solar panels are nowhere near 100% efficient and flashlights are also nowhere near 100% efficient in converting light energy to power or the reverse. The most efficient LEDs (blue LEDs doped with phosphor to make white light) are about 50% efficient in conversion that means they waste energy by heating up the LED itself and must have that heat removed to keep it from harming the LED itself. Solar panels I don't think are even close to 50% efficient but I haven't checked that out in a long time but let's say both LED (light) and solar panels are 50% efficient. You panel is bombarded by 1 watt of light and only produces 1/2 watt of energy in electricity and powers a light that outputs 50% of that power back into light yielding 1/4 watt of light.
You can see where this is going..... to nothing pretty fast.

 

[Sophrosyne]

When I was growing up perpetual motion machines were cool looking. There are many of them out there some being sold to people like converting water to hydrogen and oxygen gasses and burning the hydrogen to get power all of this is supposed to increase gas mileage.

 

[AV1611VET]

What happens if you use one of those mini-solar panels to power a flashlight, then use another one to power another flashlight, and then shine the lights at each other's panels?

It would quickly go extinct, since what you're demonstrating is evolution.

In other words, there would always be a net loss of information until ... well ... it goes extinct.

Factoid: "extinct" and "extinguish" come from the same root word.

 

[paul1149]

With every conversion of energy there is always a loss involved. Entropy. There is no perpetual motion. Over a long enough span of time all systems will run down. How long your system would stay up depends on how efficient the panels were, how efficient the bulbs were, particles in the air, etc.

 

[Chesterton]

Kind of like strapping a piece of buttered toast buttered side up to a cat's back. Since buttered toast always lands buttered side down and cats always land on their feet... Voilà! Perpetual motion!

Cats die just like batteries.

 

[Chesterton]

It would quickly go extinct, since what you're demonstrating is evolution.

In other words, there would always be a net loss of information until ... well ... it goes extinct.

Factoid: "extinct" and "extinguish" come from the same root word.

Nicely done. Hi, AV.

 

[Chesterton]

When I was growing up perpetual motion machines were cool looking.

It's funny how perpetual motion doesn't seem to go away. Mankind usually gives up on impossible ideas like alchemy or democracy eventually, but this one seems to linger on. I get the sense that everyone knows it's impossible, everyone knows why it's impossible, yet...it's so intriguing.

I wonder if it bears any relation to the desperate and futile idea of man trying to set up "on his own", without any need for what he perceives as the external God.

 

[Ophiolite]

It's funny how perpetual motion doesn't seem to go away.

That's why it's called perpetual.

 

[Chesterton]

That's why it's called perpetual.

I'd like to say I intended that as a sort of pun, but I didn't. Nice catch.

 

[AV1611VET]

Nicely done. Hi, AV.

Thank you, Chesterton!

And HOWDY back atcha!

You ain't posted in a coon's age; nice to see you posting again!

 

[jayem]

I have Atmos clock on my desk. It simulates perpetual motion. It’s a mechanical, torsion pendulum clock (the pendulum rotates alternately right and left.) It doesn’t use solar cells, it doesn’t plug into an AC outlet, and it doesn’t take batteries. It runs on a mainspring, but it never has to be wound. The movement contains a cylinder, with an accordion-like bellows inside. The cylinder is filled with liquid and gaseous ethyl chloride. This compound is very sensitive to temperature—it expands when the temperature rises, and contracts when it falls. This action moves the bellows back and forth. Then there’s a very finely machined mechanical linkage from the bellows to the mainspring, which powers the movement. The spring is initially wound when the clock is made at the factory. But after that, subsequent fluctuations in ambient temperature—as translated into motion through the bellows mechanism—keep the spring wound. It’s said that a 1 degree Celsius temperature change per day can keep the clock running for 2 days. I have the clock near my desk lamp. Which I keep on for 6 or 7 hours a day. This provides enough temperature change to keep it going. It’s not a cheap clock. All the mechanical parts are must be precisely made and finished to minimize friction and wear. And obviously, it’s not perpetual motion. It’s powered by fluctuations in heat energy. But it’s a very cool device. And for a mechanical clock, it keeps darn good time.

 

[Chesterton]

I have Atmos clock on my desk. It simulates perpetual motion. It’s a mechanical, torsion pendulum clock (the pendulum rotates alternately right and left.) It doesn’t use solar cells, it doesn’t plug into an AC outlet, and it doesn’t take batteries. It runs on a mainspring, but it never has to be wound. The movement contains a cylinder, with an accordion-like bellows inside. The cylinder is filled with liquid and gaseous ethyl chloride. This compound is very sensitive to temperature—it expands when the temperature rises, and contracts when it falls. This action moves the bellows back and forth. Then there’s a very finely machined mechanical linkage from the bellows to the mainspring, which powers the movement. The spring is initially wound when the clock is made at the factory. But after that, subsequent fluctuations in ambient temperature—as translated into motion through the bellows mechanism—keep the spring wound. It’s said that a 1 degree Celsius temperature change per day can keep the clock running for 2 days. I have the clock near my desk lamp. Which I keep on for 6 or 7 hours a day. This provides enough temperature change to keep it going. It’s not a cheap clock. All the mechanical parts are must be precisely made and finished to minimize friction and wear. And obviously, it’s not perpetual motion. It’s powered by fluctuations in heat energy. But it’s a very cool device. And for a mechanical clock, it keeps darn good time.

So aside from eventual wear and tear (even though minimized) what will make the clock stop working?