But a good effort, nevertheless.

More careful reading would've revealed that nobody said "there isn't enough power on USB to run that light bulb", rather "do that" would obviously be the end result reported about.

Further, if you ran a 2.8V bulb off 5V it'll use more than 0.3a and immediately burn out so obviously it was further current limited. Given a concentrated enough heat it could pop a little but not enough to make it worth the effort or have a snack in a reasonable amount of time.

The disappointing part is to generate more heat to do it instead of using the waste heat from the proceessor. Mount a little aluminum pot with copper bottom over the processoor and you'd have a more suitable and more green popcorn maker, if only you found the load level that keeps the CPU from frying itself.

naah, the movie would be over by the time all the popcorn has popped, besides I'm having trouble believing it actually works because there's a cut in the middle of the video clip where suddenly it's full of popcorn, whereas I CAN believe this USB powered meat cooker is real, granted it does use the power from 30 USB ports...

http://xe.bz/aho/24/

What in god's name kind of film fanatic would watch a movie on his laptop!?

USB is spec'ed to provide at least 2.5 watts (.5A at 5V) but any individual implementation is free to provide more. Still the question remains how much power is required to get the bottom plate of this device to the required 400 degree F to pop the corn.

I like popcorn. Is there an icon for that?

Any kernel directly in contact with the light bulb might get hot enough to pop, but I doubt the rest would go without a lot of shaking to get each one in turn to touch the bulb.

They poured a small amount of liquid (vegetable oil?) in too; that might have helped transfer heat from the bulb to the kernel.

Also, I reckon the grey gunk was metal-loaded epoxy, not thermal grease. I wouldn't want to eat silicone grease...

The 2 bulbs were sealed into a jar cap that was in turn glued onto the bottom of the tin can, the majority of the heat generated by the bulbs would be trapped and transfer through the bottom of the can where gravity holds corn kernels against the hot parts with oil added for better heat transfer.

The whole can doesn't have to hit 150C and the 'Thermal grease' is on the outside of the can and so doesn't come into contact with the popcorn.

I note an insulator/reflector added to the jar cap, the fact that we can clearly see corn popping before he puts the jar over the top (and while in place), and that on pouring out the popcorn the base of the can shows heat discolouration. Looks like he shockingly cut out ten minutes of cooking time, which is a shame as that would have put this short film right up there with the You Tube classics "my kettle boiling" and "paint drying on sunny day"

Not Fake but I doubt those bulbs would operate for very long making for some expensive pop corn regardless*

*and yet still cheaper than you can buy it at the cinema.

If we assume that we want to heat 10g of popcorn to 150C , then by my calculations:

Using Specific Heat Capacity:

q = mct

c = 4200, t = 130, m = 0.01

Therefore:

q = 4200 * 130 * 0.01 = 5460 J

Now Power is Joules per Second:

p = q / t

p = 2.5 , q = 5460

Therefore in order to raise the temperature of 10g of pop corn to 150C at maximum USB power it would take:

5460 / 2.5 = t = 2,184 Seconds = 36 Minutes

This assumes that heat transfer is 100% efficient and there is no heat loss.

Now providing that the heat input into the system is greater than the heat loss, there should eventually

be some popcorn.

I think the more interesting question is how long it took.

Another thing to note, is that the USB bus does not provide 500mA of power unless requested by the device.

Therefore it is likely in this situation the USB bus is only providing 100mA, IE 0.5W

But that is just my views.