What's a geiger counter?

[simpleguy45]

Geiger counter
How does it work?
What does a Geiger counter click mean?
What does this have to do with ionization and gas?
What does this have to do with electrons?
What should we know about it for MCAT?

please help

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[msamp]

http://en.wikipedia.org/wiki/Geiger_counter

 

[argama]

in movies it's that wand-looking thing that makes clicky noise until the main character finds he/she is about to be attacked by a radioactive monster and/or he/she finds him/herself about to enter a nuclear test site filled with mutants. Then the counter goes beserk w/lot of clicking and breaks

In all seriousness, I don't think we need to know the details of what it does....the passage in the MCAT should give enough info to figure it out.

 

[going2breakdown]

When something radioactive decays it sends out some sort of particles or gamma rays. If these particles (or the photons) have sufficient energy they will cause the gas in the Geiger counter (Argon? it's one of the noble ones I think) to ionize. When this happens the circuit in the counter is complete and it makes a "click" so, for each particle that smashes ionizes the gas you get a click. One decay, one click. I would read the wikipedia article though. I think this is how it works, think of it like this if all else fails.

Oh, know the types of decay for the MCAT too. What is beta - beta + alpha, and gamma decay (if they don't say beta plus they mean beta minus, assume beta minus unless it says specifically beta plus), eekk! and electron capture. https://www.aamc.org/students/download/85562/data/ps_topics.pdf you can find this on wikipedia, or in a review book of some kind. Hopefully someone else will be able to help you better. Sorry.