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Re: [Phys-l] flashlight : no battery, no bulb

I am not thrilled by a bold assertion of "no way".
I take it, there is some evidence backing this assertion?

Something that makes the advertising claim of "Up to five
minutes light from a thirty second shake charge" an
actionable falsehood?

Brian W

At 12:14 PM 6/2/2008, Jorge Hoyos, you wrote:
Indeed, no bulb, but they do need battery. No way a
long lasting charge only shaking them.

--- John Denker <> wrote:

> The local Walgreens stores are running a clearance
> on flashlights.
> This is the kind with an LED instead of a bulb, and
> a supercapacitor
> instead of a battery. You charge it by shaking.
> The chassis is
> transparent, so you can see the coil and the magnet.
> I like them because
> -- light weight ==> good for hiking
> -- no battery ==> near infinite shelf life
> -- LED won't burn out any time soon.
> -- small amount of shaking makes rather
> long-lasting light
> -- physics lesson
> -- on sale for $2.00
> On the other hand, it looks like they were having
> serious production
> problems. I had to sort through 12 of them to find
> 3 that worked.

Brian Whatcott Altus OK Eureka!