Comments by "roidroid" (@roidroid) on "TED-Ed" channel.

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  10. Brandan09997 i scoff when i look at a shiny 3D rendering of a futuristic phone, with a caption reading "This amazing phone's charge could last for 100 years and be powered by unicorn farts, kitten giggles, & quantum woowoo", yes. Any designer can render & write whatever fictional story they want to go with the artwork for their fictional devices, but actually constructing a device that will function under the known laws of physics is another story. Sadly, designers often aren't trained too well in this. It's easy to design a (effective & competitive) hand-held laser pistol, low power prototypes already exist, hell you can watch real videos here on youtube of people's DIY pulsing laser blasters, it's known tech. What's hard though is powering it (to a sufficient level) with known battery tech, that's typically the limitation in the real world: the density of energy storage. Another one is the economics of actually constructing the device (It's common to see designs for all sorts of things that stipulate ridiculously expensive materials, or construction techniques which are still barely being understood in universities - let alone in use in industry right now). Most of these things are "what if". But sadly the media reports on them as if they're just around the corner. This serves both the design firms and the media well, they're generally more interested in page views and SEO exposure ratings than any sort of accuracy in reporting. To answer OP's question directly: TBH the reason we don't all have exoskeletal power armour is because we're civilians and have little need for armour. But the reason we don't have exoskeletal suits is because they're a relatively new tech. Exoskeletal suits already exist right now in a primitive (still mostly prototype, unaffordable) form, but it's good enough to predict that they'll be cheap and commonplace tech perhaps within 10 years, we'll get there with slow incremental improvements alone. No exotic materials needed, OP is in luck, we just need time. I'm glad OP didn't ask for (useful) personal jetpacks tho, that's a much harder nut to crack. Sorry, no flying Ironman suits for a while yet.
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  26. nitwndr The battery continues to (try to) supply power (somewhere between 2.5V and 4.2V) to the phone at the same time as the charger is supplying 4.2V to both the battery and the phone, the 2 sources are connected in parallel, so the phone only ever sees 4.2V like usual. It's all connected to the same single terminal: the positive of the phone, positive of the battery, and positive of the charger. A fully charged battery will supply 4.2V to the phone, an almost discharged battery will supply maybe 2.5-3V. When the battery is being charged - the charger supplies 4.2V positive to the battery's positive terminal (ie: it's in parallel). So as far as the phone is concerned it just sees 4.2V positive on it's positive terminal, just like usual, all that's changed is that there's slightly more amperage at it's disposal (comming straight from the charger). Inside the battery though is where things are different, it's suddenly seeing voltage at it's positive terminal (from the charger) which is comparitively MORE POSITIVE than it's own positive 2.5V. You have to remember that voltage is a relative thing. This means that to the battery - if it's charging it's own positive terminal to 2.5V positive, but there's an outside positive voltage of 4.2V, then what it's actually experiencing inside itself on it's positive terminal is 1.7V of NEGATIVE charge. The battery's own residual 2.5V positive is cancelling out 2.5V positive of the incomming 4.2V, (it experiences that 4.2V positive as relative to the 2.5V positive that the terminal already had) thus leaving a RELATIVE voltage difference of 1.7V in the other direction (ie: negative). So yeah, while charging there is indeed a reversal of voltage going on, but it's only the inside of the battery itself that is experiencing it. :) It's like having a bucket that is pouring it's water out onto the ground slowly, and you're occasionally topping up that bucket with a glass of water. The water pouring out from the bucket never stops, and the level in the bucket is normally going down. But when the glass is topping up the bucket - the water level in the bucket suddenly starts going up (this is like the internal reversal of voltage the battery is experiencing, the weird experience of it's water level going BACKWARDS is only experienced by the bucket itself and no-one else), even though the water pouring outof the bucket isn't effected and just keeping going during the whole process. My point is that when you are recharging that bucket, it doesn't effect the pouring out of the bucket's water onto the ground, it certainly doesn't make the pouring go in reverse. The only reversals that are happening are within the water-currents of the bucket itself. I hope that helps :)
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