What radioisotope makes watch hands glow in the dark?

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j_s_j_c_c

So I did this practical about the penetrating power of radiation, and there's a question which asks: "Some watches use emitting radioisotopes to make the hands glow in the dark. Comment on the safety implications of this method." So there's this gap between 'use' and 'emitting' and it think its supposed to say alpha, beta or gamma (but with the symbol). I can answer the question if I knew what kind of radioisotope made the watch hands glow and what kind of emitter it is. So any help would be appreciated.

Answer
There have been a few different compounds used to luminesce watch markers.

Most modern quality watches used Luminova, a brand name for a Strontium Oxide Aluminate compound.

Ball watch uses Tritium micro gas tubes, which do not require charging, but will stop glowing as the radioactivity of the tritium runs out.

Some older style watches used a Radium based compound for their glow paints.

Runners: what device can be used to measure the speed and distance that you run?

Peter_33

I am not interested in the Ipod-Nike shoes. I liked more the bracelet that connects to the Nike shoes.

But I am not interested on buying running shoes. All I need is the device that you can carry with you (watch kinda thing)
What brands and models can you recommend?

Answer
Hello,

I run with the Garmin Forerunner 201...and I love it. It instantaneously tells me my pace, distance and time. I use it for marathon training and races from 5k to 26.2. It also has a lot of interval and mapping features...very cool toy. The 201 is an older generation. I'd check out the 205, 305, and 405. See the review below. Good luck!

- Mike

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