I love the practical way the neo-liberal UK government make things happen to create a more 'business friendly' environment. The latest idea is to simplify science exams to allow more people to pass GCSE physics - what could be wrong with that? More scientific people and we'll surely have a more scientific country.
I had a look at the example physics paper here and tried myself out - I scored 38/40 'correct' questions, although sometimes I answered with what the examiner might have in mind as correct, as oppposed to my own viewpoint.
So which questions did I 'fail'?
They see many stars like our Sun.
The colours are different depending on the age of the star.
Which is the colour of the star between the stage between yellow and white?I'm not convinced stars are ever yellow - isn't that something to do with the Earth's atmosphere? I answered 'red' instead of 'blue'
Chei and Jaz are told that stars will eventually cool so much that they no longer glow. These cooled stars could still be detected by taking photographs using:
a. Gamma rays
b. X-rays
c. ultraviolet
d. infraredI answered 'gamma rays' without thinking about whether or not you can take pictures of gamma ray emissions. I'm not sure if a star is no longer emitting visible light, it will still be emitting infrared either, and the correct answer of 'd' doesn't seem that correct to me.
Syndicate Blogs
IAAA (I am an astrophysicist)...
And this paper absolutely appalled me. I was seething. Your subtle irony almost had me, though, and was about to post a long comment-rant here, until I noticed you'd posted under 'Rants'!
Unfortunately, the idiots responsible for our education system would be oblivious to your wit, taking it to be high praise.
Re: IAAA (I am an astrophysicist)...
Yes, the paper was really dumb. What worries me is that the people who prepared it didn't seem to actually understand what physics or the scientific method were about. Maybe a third of the questions were reasonable and actually about physics, and the remainder were either off-topic or just wrong in some way.
The exams are now prepared by private companies, rather than state examination boards - I assume exams which are easier to pass will sell better. Then their incorrect viewpoint is imposed on children who do nothing at school but learn how to pass these useless tests.
What exactly is a question like this trying to test:
Where is the physics? It wouldn't even be a particular good or interesting question in a pub quiz.
Hmm...
I was under the impression that blue stars were at the top of the development chain, and red stars were at the bottom. Blue stars are really, really hot, and red stars are very cool...
Black Body Curve
To answer both of your questions at once, you need to consult the standard black-body radiation curve. The curve basically states that at a given temperature, the strongest wavelength of an emitting body will be at a certain wavelength. The sun's temperature of about 6000K corresponds to a peak near yellow. If it's temperature was 600K, it'd be more likely to be red (like a stove element). At 300K, you'd likely only see it in infrared, and so forth.
This is correct as far as it
This is correct as far as it goes, but the questions are both incorrect in their assumptions. The colour of a star is not only determined by the stage in its life, but also by its
* mass (one factor in the star's temperature as it determines how rapidly it undergoes fusion);
* chemical composition (leads to absorption/emission lines on top of the blackbody spectrum and can affect the rate of fusion or enable additional fusion reactions to occur);
* and velocity (the colour is redshifted/blueshifted depending upon the motion of the star). The velocity becomes important in multiple star systems and in those that are farther away (which tend to be moving more rapidly).
* probably some other things too
Re: This is correct as far as it
Yes, excellent answers. Thanks for the replies - A grades deserved all round I say. I went and had a look in Wikipedia at the 'Stars' and 'Black body' entries and they were really good. I'm now happy that the Sun is mostly yellow because of it's temperature and chemical composition. At night, none of the other stars look yellow to me though - they are either white or bluish. And the red shifted ones receding at high speed are too far away to be seen without a telescope I suppose.
heh
> I'm not convinced stars are ever yellow - isn't that something to do with the Earth's atmosphere? I answered 'red' instead of 'blue'
Stars emit light stronger in some colors (wavelengths) that others. Look at the controls for your monitor for example. The color correction of whiteness will be measured in terms of the color of light emitted from a star (black body) with a surface of X Kelvin.
For example, our Sun has a surface temperature of 6000K, which looks kinda yellow.
You can take pictures of gamma rays btw. That was actually how radioactivity was first discovered. Rutherford wrapped some paper around uranium salts, then wrapped photographic film around that. In the morning he found that the photographic film was black.
JohnFlux