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Post by ironhold on Nov 16, 2012 22:45:17 GMT
linkOver on another board I go to, we've got a newbie with some misbegotten notions about science. Right now, her big thing is that she has an idea for a power amplification system consisting of a light bulb that shines into a solar panel. She seems to believe that it would be some sort of perpetual motion machine, in that for a small amount of juice to the light bulb an even bigger amount of juice would be gathered by the panel. How can we politely yet definitively tell her that it's not gonna work? Thanks.
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Post by Cybermortis on Nov 16, 2012 22:55:18 GMT
Even the best solar panels capture only 21% of the energy of sunlight, and even if you specifically designed the panels to capture light at the frequencies produced by a light-bulb this would only increase the figure to around 30%.
So a 100 watt light-bulb illuminating a solar-panel would only give you 30 watts worth of energy at best.
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Post by GTCGreg on Nov 16, 2012 23:49:08 GMT
So a 100 watt light-bulb illuminating a solar-panel would only give you 30 watts worth of energy at best. And for that 30% figure to work, the light bulb would have to be 100% efficiency, which, of coarse, it isn't. |
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Post by memeengine on Nov 17, 2012 0:01:08 GMT
So a 100 watt light-bulb illuminating a solar-panel would only give you 30 watts worth of energy at best. Actually, the 100 watt rating of the bulb is a measure of the power consumption not the light power emitted. For the old style incandescent bulbs the light output of a 100 watt bulb could be as little as 5 watts, with most of the rest lost as heat. Even the most efficient of the new designs still produce some waste heat. You also have to consider that not all of the light from the bulb will fall on the solar panel (even with reflectors). So there will be losses in the bulb, losses in light transmission, losses in the solar panel and losses in the electrical circuit connecting the panel to the bulb. So I think you'd have real trouble getting near to 30% efficiency in terms of electrical conversion. |
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Post by Cybermortis on Nov 17, 2012 0:04:30 GMT
All true, I was just oversimplifying things to demonstrate the basic problem.
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Post by freegan on Nov 17, 2012 0:54:01 GMT
Just tell her to wait until she's done some more science classes before posting such ideas again.
(Surely the forum has a lower age limit in its terms of service.)
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Post by ironhold on Nov 17, 2012 2:24:24 GMT
Just tell her to wait until she's done some more science classes before posting such ideas again. (Surely the forum has a lower age limit in its terms of service.) Sadly, she appears to be an adult; she's requested permission to join an 18+ "politics" sub-forum. |
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Post by freegan on Nov 17, 2012 3:49:32 GMT
Just tell her to wait until she's done some more science classes before posting such ideas again. (Surely the forum has a lower age limit in its terms of service.) Sadly, she appears to be an adult; she's requested permission to join an 18+ "politics" sub-forum. Remind her that "18+" is a reference to age, not IQ. Seriously? Just point her at en.wikipedia.org/wiki/Conservation_of_energy and tell her to follow all the links until she understands what she's reading. |
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Post by srmarti on Nov 17, 2012 5:27:08 GMT
Sadly we saw it posted more than once before. Either pointing out the efficiency and losses will get the idea across or it will be hopeless and they'll argue the point.
Tons of those topics seem to be popping up on the new Mythbuster board. I'm not going to get sucked into posting explanations this time. The new format probably makes it not worth bothering. It's not really a discussion anymore.
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Post by trakmec on Nov 17, 2012 6:40:40 GMT
All of the basic math and science is already posted here above. Perhaps it could be suggested that she spend the $10.00 at Radio Shack buy a small scale solar panel, socket and bulb and report back? If she’s stubborn and close minded you won’t affect her, we all know this from past conversations with similarly minded people.
Rather though if she’s passionate about this than maybe experimenting will get her to use her own mind to think and test her own ideas. Even if we here already know the outcome, it may spark her imagination.
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Post by silverdragon on Nov 17, 2012 9:30:00 GMT
Converting one form of energy to another ALWAYS produces loss.
The more you convert, the more loss.
Loss is easily detected if its heat....
I have never seen a 100% "efficient" machine that converts energy....
Heck, even the SUN looses vast amounts of power doing that...
And that is good for us, as thats the heat that keeps us all warm.
Ask her to put a hand near the light bulb... if it gets warm, ask her where that is coming from......
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Post by freegan on Nov 17, 2012 10:46:08 GMT
Perhaps her confusion arises from the term "Power Amplifier".
Explaining to her that power amplifiers do not amplify power may clarify her misconception.
They take an input (usually a low power signal), use an external power source and output a higher power signal to, typically, drive a loudspeaker or radio antenna.
In effect, they CONSUME power to amplify.
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Post by trakmec on Nov 17, 2012 16:51:34 GMT
Ummmm…. ironhold I’m a bit confused. I didn’t see the site link yesterday, but isn’t that a Battle Mech Fan site? So what nicewhich was referring to is a sci-fi engine in a made up Mech isn’t it? So for Battle Mech that idea works, even if in reality it doesn’t.
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Post by Cybermortis on Nov 17, 2012 17:14:00 GMT
Battle Tech is based in 'Hard' science, meaning that all the technology - except that of faster than light travel and FTL communications - is based on known laws of science.
No perpetual motion, no violating the laws of conservation of energy. Even Mech's themselves conform to known laws of physics in everything from the materials used to construct them, through the systems that move them and through to the weapons they use - the latter even have 'real world' limitations, such as Lasers not being all that effective underwater.
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Post by ironhold on Nov 17, 2012 19:15:57 GMT
Battle Tech is based in 'Hard' science, meaning that all the technology - except that of faster than light travel and FTL communications - is based on known laws of science. No perpetual motion, no violating the laws of conservation of energy. Even Mech's themselves conform to known laws of physics in everything from the materials used to construct them, through the systems that move them and through to the weapons they use - the latter even have 'real world' limitations, such as Lasers not being all that effective underwater. Thank you. You'd be surprised just how many scientific discussions I've gotten into over the years on some of the different BTech boards I've been on. |
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ronbo6
Demi-Minion
Survivor: End of the World. 12/21/2012
Posts: 91
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Post by ronbo6 on Nov 18, 2012 2:39:03 GMT
Converting one form of energy to another ALWAYS produces loss. The more you convert, the more loss. Loss is easily detected if its heat.... ...and/or sound. Losses are less easily detected (but can be still present) as emissions in any and all the other frequencies in the electromagnetic spectrum. Light, heat, and sound frequencies are only three pretty narrow bands in this spectrum. |
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Post by the light works on Nov 18, 2012 15:35:07 GMT
Converting one form of energy to another ALWAYS produces loss. The more you convert, the more loss. Loss is easily detected if its heat.... ...and/or sound. Losses are less easily detected (but can be still present) as emissions in any and all the other frequencies in the electromagnetic spectrum. Light, heat, and sound frequencies are only three pretty narrow bands in this spectrum. to spell it out, "loss" is emission in any other form than what you are desiring. "halogen" cooktops lose energy in the form of light. but some people like them because they emit that red glow which they interpret as "hot" |
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Post by WebDragon on Nov 19, 2012 3:20:59 GMT
I have never seen a 100% "efficient" machine that converts energy.... There was a discussion several years ago @ Disco about electric heaters being the most efficient energy transfer. While they ARE incredibly efficient, I suggested that the slight acoustic hum inherent via AC was a loss. I think it was Spork (ziploc) who suggested that the miniscule audio component will eventually dissipate into heat. Blew my mind.  Not considering any "line loss" in delivering the power, it was the general consensus that an electric heater was virtually 100% efficient. |
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Post by spork on Nov 19, 2012 14:40:15 GMT
I suggested that the slight acoustic hum inherent via AC was a loss. I think it was Spork (ziploc) who suggested that the miniscule audio component will eventually dissipate into heat. Blew my mind. I don't recall that particular exchange. I think I recall a similar exchange in which someone suggested that some of the emissions would escape through the window as photons and leave our atmosphere without being converted to heat. But I'm curios about what part of your exchange blew your mind? |
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Post by the light works on Nov 19, 2012 15:47:26 GMT
I suggested that the slight acoustic hum inherent via AC was a loss. I think it was Spork (ziploc) who suggested that the miniscule audio component will eventually dissipate into heat. Blew my mind. I don't recall that particular exchange. I think I recall a similar exchange in which someone suggested that some of the emissions would escape through the window as photons and leave our atmosphere without being converted to heat. But I'm curios about what part of your exchange blew your mind? I thought that was in a conversation about whether all energy ultimately ends up as heat. but yes, I tell customers that all electric heaters are equally efficient about turning electricity into heat - though each has different delivery characteristics. |
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