Quiz question

[Space cat]

This question came up on Eggheads today and their 'right' answer was wrong! Just out of interest, I'd just like to see what everybody else thinks.

 

[snico]

Gamma Rays?

 

[Alarm]

Is it not gamma?

 

[hotrod]

I know nothing about this stuff but I've gone for gamma - method in my madness. Probably completely wrong .

 

[Mickymoody]

This question came up on Eggheads today and their 'right' answer was wrong! Just out of interest, I'd just like to see what everybody else thinks.

Not on the version of Eggheads that I watched...maybe you live in outerspace?

 

[Space cat]

maybe you live in outerspace

That's as good a place as any for a space cat but, like it says at the bottom, we don't know where we are.

Edit: Ten votes isn't very many but I see a clear leaning towards gamma rays. I'll let a few more come in before I tell you what I think.

 

[joe-90]

Do all of those wavelengths travel at the same speed as visible light? Just wondered.

 

[Space cat]

Do all of those wavelengths travel at the same speed as visible light? Just wondered.

In a vacuum, yes. They're all electromagnetic radiation and they all obey Maxwell's equations, from which their speed can be derived.

 

[Crickleymal]

It's not clear cut. According to Wikipedia http://en.wikipedia.org/wiki/Gamma_ray (which of course may not be right) there is a considerable degree of overlap between gamma and X rays. I seem to recall when I did physics at school my teacher saying something like X rays and gamma rays are the same thing. Mind you that was 30 years ago so make of that what you will

 

[toasty]

I'd say,

X-rays have a wavelength in the range of nanometers (10^-9 meters)
Gamma rays are in the range of picometers (10^-12 meters)
Radio waves are massive, say 1 meter

Obvioulsy its' between X and Gamma rays.
I'd go for Gamma rays.

I'd also argue (and I know there is more to it than this) but in this case it's the sort of answer you could work out given that a sheet of lead will block radio and x-rays, but not Gamma rays

Dan

 

[matt1e]

I'm going for Gamma too

 

[Space cat]

So a week has gone by and there's a clear majority in favour of gamma rays. I suppose a lot of us remember the old chart on the wall of the school physics lab; the one that showed the electromagnetic spectrum with X-rays lying between UV and gamma.

But that chart is out of date. Crickleymal has the answer; X-rays and gamma rays are the same thing. The names are historical. X-rays were first observed coming from a thermionic diode running at a very high voltage while gamma rays came from radioactive atoms. It was only later that physicists realized they were both electromagnetic waves so the names have stuck. The generally accepted definitions today are that gamma rays are nuclear in origin whereas X-rays are emitted when electrons lose energy. Wavelength is inversely proportional to energy so it's much easier to ask the question, "which have the highest energy"?

In the early days, X-ray energies were limited by the energy levels available within atoms or the voltage that could be applied to an X-ray tube - a few hundred keV at best. Gamma rays from natural radioactive sources can be much higher than this - eg 2.4 MeV from Bi214 - though most are quite low. Today, gamma energies are still limited by the nuclear reactions that can produce them (fission, fusion, decay) but X-ray energies are limited only by the machine that accelerates the electrons. Fifteen MeV is a popular choice for radiotherapy but that's nothing compared to what you could find in a research lab!

So, to return to the original question, which is it to be: X-rays or gamma rays? I would say X-rays though I'm prepared to have a nuclear physicist prove me wrong. At the very least, the question was badly posed with no clear-cut answer. It certainly wasn't fit for Eggheads!

 

[Alarm]

So at the end of this you admit it is 50/50




Doh..................!

 

[Susiejb]

So at the end of this you admit it is 50/50




Doh..................!

......and I haven't slept a wink all week for worrying about it

 

[cantaloup63]

......and I haven't slept a wink all week for worrying about it

Oh contraire - it's been quite soporific. Is it safe to wake up yet