Shake Torch / Flashlight

These torches became very popular in south Africa a couple of years ago when we were plagued with blackouts.

It consist of a coil of copper wire with a magnet in the centre that slides through the copper coil when shaken. This action creates an electrical current in the coil, which in turn charges a rechargeable battery (or super capacitor).

This action is known as Faraday’s induction, something that we learned in high school.

These torches are very impressive when you buy them – one hardly needs to shake them and they give a decent light from the LED.

Unfortunately the fun ends as soon as the internal battery gets flat. You then need to permanently shake the torch to get the LED light to shine bright. The problem is shaking the torch only generates a very small current to charge the battery – you will get roughly 10 seconds of light from 10 seconds of shaking –  quite hard on the elbows!

I’ve even seen some of these torches that didn’t have a rechargeable battery – they use a small lithium battery that last quite long, but after that it’s impossible to store the charge.

My conclusion:  I’m afraid this is only a cool gadget – fun to play with, but not really useful.

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