IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: falafail on April 24, 2010, 02:54:58 pm

Title: CIE physics
Post by: falafail on April 24, 2010, 02:54:58 pm
in the syllabus it says, "show an undrstanding of the existence of discrete electron energy levels in isolated atoms and deduce how this leads to spectral lines"

are spectral lines produced when an excited electron goes back to its ground state? because it emits photons? is that it?  :-\
Title: Re: CIE physics
Post by: ~ A.F ~ on April 24, 2010, 02:59:21 pm
Yuo thats kinda true..visit http://www.s-cool.co.uk/alevel/physics.html  for more details and animations
Title: Re: CIE physics
Post by: falafail on April 24, 2010, 03:07:23 pm
Yuo thats kinda true..visit http://www.s-cool.co.uk/alevel/physics.html  for more details and animations
::)


"The lines on the spectra are the frequencies of light that exactly match the energy required to make the jumps between energy levels."
right now i'm confused.
are the lines caused by the emission of photons, or the absence of those particular frequencies of light? can someone please explain this?
Title: Re: CIE physics
Post by: astarmathsandphysics on April 24, 2010, 08:15:35 pm
There is a page on my website. Will post the link when I get home
Title: Re: CIE physics
Post by: T.Q on April 24, 2010, 10:04:38 pm
::)


"The lines on the spectra are the frequencies of light that exactly match the energy required to make the jumps between energy levels."
right now i'm confused.
are the lines caused by the emission of photons, or the absence of those particular frequencies of light? can someone please explain this?

check this http://physics-edu.org/line_spectrum_of_hydrogen_atom.htm (http://physics-edu.org/line_spectrum_of_hydrogen_atom.htm)
Title: Re: CIE physics
Post by: falafail on April 24, 2010, 11:10:14 pm
nevermind, got it. thanks anyway. :D

there's something else i don't get though...
show an understanding of how the force on a current-carrying conductor can be used to measure the flux density of a magnetic field using a current balance  ???
Title: Re: CIE physics
Post by: astarmathsandphysics on April 25, 2010, 10:46:50 am
A hall probe is easier to use. I am looking for a simple explanation of how current balances work. I dont understand at the moment why it doesnt work the same as a dynamo
Title: Re: CIE physics
Post by: astarmathsandphysics on April 25, 2010, 10:56:37 am
http://images.google.co.uk/imgres?imgurl=http://cla.sd57.bc.ca/~rgiroday/Physics12.0809/unit7/U07L04/currentbalance1.gif&imgrefurl=http://cla.sd57.bc.ca/~rgiroday/Physics12.0809/unit7/U07L04.htm&usg=__75ckyJLYFaW03JyEISNFwrylfj0=&h=415&w=548&sz=16&hl=en&start=1&sig2=T7w9-HUDrwP9btU0IWxc5g&um=1&itbs=1&tbnid=wHIm-mKtLEKpZM:&tbnh=101&tbnw=133&prev=/images%3Fq%3Dmeasuring%2Bmagnetic%2Bfield%2Busing%2Bcurrent%2Bbalance%26um%3D1%26hl%3Den%26client%3Dsafari%26rls%3Den-gb%26tbs%3Disch:1&ei=lRHUS80GyZM4kv2x0w0


expained here
Title: Re: CIE physics
Post by: falafail on April 25, 2010, 05:39:42 pm
A hall probe is easier to use. I am looking for a simple explanation of how current balances work. I dont understand at the moment why it doesnt work the same as a dynamo

what's a dynamo?
and could you explain how hall probes are used as well? please & thank you.
Title: Re: CIE physics
Post by: astarmathsandphysics on April 25, 2010, 09:30:37 pm
A dynamo is just a wire loop that turns in side a magnetic field and so generates a current.
A hall probe measures a magnetic field by measuring the force on a current carrying conductor in a magnetic field
Title: Re: CIE physics
Post by: dodo on April 26, 2010, 03:49:14 pm
please check may/june 2009 CIE physics AS unit 2
question number 5 b)
please i need the reply as soon as possible
and if please with the explanation how u got the answer :)
Title: Re: CIE physics
Post by: nid404 on April 26, 2010, 03:52:06 pm
I do cie so i don't have the paper...and i find it diff to figure on freeexampapers...
it'll be gr8 if you can upload it
Title: Re: CIE physics
Post by: astarmathsandphysics on April 26, 2010, 10:29:53 pm
Do you mean paper 2