28/02/18. If you’re stuck inside- DON’T go on your X-boxes, PS4 or whatever the latest number try doing some timed papers.
To the student’s sister who needs the Quantity, Units, Symbols etc .I’ve uploaded the old pre-CfE version and you can just add the additional few. Check out Int1-AH many are relevant. Missing would be t’, l’ etc.
If there is a snow day tomorrow, use the time to look at the EMF material and the test will be as soon as we get back.
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This is a ten week revision plan, put together by Mr A Riddell from “up North”. It will give you some ideas on how to break up the daunting task of revision. You don’t have to complete this in the same order, but it does give an indication of how much you need to cover in one week.
I received this card several years ago (thank you Mr and Mrs Long), and it shows Physics in the animated world!
My immediate reaction to the card was “What big ceilings you have Chudleigh.”
With a stopwatch and the assumption that g remains constant Higher and A level students should calculate the minimum height of the room Chudleigh finds himself in. With love and best wishes Mrs Physics.
Make sure you add your answers in the comment box below! Working optional
Time for cork to go up and return on average 6.6 s.
That gives a time to reach the max height 3.3 s
At height v=0, a=-9.8 ms-2, t=3.3s.
Using s=ut+1/2 at2we can estimate the maximum height the cork reaches
Now the best way to work out s is putting this result into the equation for height
Now I don’t advertise on this site, but if Jacquielawson.com allows me to keep this up then I assure you I am happy to link and tell you that this site contains the best e-cards you can want and for the unlimited number you can send it is worth every penny. They really do cheer up people
A discussion on the Physics
Teachers’ Network requested advice on “What is the biggest ever redshift
detected?”
Research shows it was a
redshift, z = 11.09 for galaxy GN-z11; and the measurements were taken in the near infra red using Hubble’s
Wide Field Camera.
This is a big question because
effectively we are seeing the furthest galaxy back in time. It is 32.2
billion years away and came into existence 400 million years after big bang. So if the Universe is only 13.8 billion years
old then how come we can see something so far away?
During this time the Universe was
opaque and full of neutral atoms.
Professor Martin Hendry supplied an interesting reply.
In
some cases we can determine the redshift of a galaxy by measuring the
wavelength of a particular spectral line that corresponds to a particular
transition of an electron in a hydrogen atom. For example the Lyman alpha
emission line is the result of an electron dropping down from the n=2 energy
level to the n=1 energy level, and the presence of this spectral line is often
seen as an indicator of a recent burst of new stars forming as one might expect
to see in a very young, recently formed galaxy. (This line was proposed
as a tell-tale sign of a very young galaxy by Bruce Partridge and Jim Peebles –
awarded the Nobel Prize for physics this week: see e.g. https://en.wikipedia.org/wiki/Lyman-alpha_emitter). This line has a wavelength of
121.567 nm in the rest frame of the hydrogen atom. If a galaxy is a
strong Lyman alpha emitter, and the line is observed at wavelength lambda, then
by comparing the observed wavelength with the 121nm at which it was emitted we
can measure the redshift of the galaxy.
(Of course if this spectral line is redshifted then how do you know it’s a Lyman alpha line? Likewise for any other spectral line. Often it’s the combination of several spectral lines and their relative spacing that gives the game away – a bit like a bar code in the supermarket. You could imagine enlarging the image of a bar code in a photocopied and, generally, it’d still be recognisable as the overall pattern would still be the giveaway).
In
fact for this record-holding galaxy, the redshift was determined a slightly
different way, from the Lyman series but not the Lyman alpha line and not from
an emission line but an *absorption* line: specifically it was
determined from the “Lyman break” – i.e. the limiting wavelength that
corresponds to the amount of photon energy you need to absorb to allow an
electron in the n=1 energy level to escape from its hydrogen atom
altogether. That is a higher energy (and so a higher frequency, and
a shorter wavelength) than the Lyman alpha line, and in fact corresponds to
about 91 nm in the rest frame of the hydrogen atom. Any photons
that have even higher energies (and thus even shorter wavelengths) than this
get absorbed by the (lots of) neutral hydrogen that is around in the Universe
at that time; these photons thus *ionise* that neutral hydrogen.
This is sometimes referred to as “re-ionisation” in the sense that the universe
was fully ionised when it was much younger, because it was much hotter, then it
cools enough for neutral hydrogen to form – i.e. when the CMBR was emitted –
and now it’s being ionised again. Where are the high-energy photons
coming from to do this ionising (being absorbed in the process)? They are
believed to come from hot young stars – i.e. the newly formed stars in these
young galaxies. (Remember, the more massive the star the hotter their
surface temperature, so massive blue stars emit lots more of these energetic
photons than cooler red stars do).
So,
in summary, the spectrum of light from a galaxy as a whole drops off at the
Lyman break, like a “cliff edge” because at shorter wavelengths than the Lyman
break these photons get absorbed, ionising the hydrogen gas in their
environments.
You
can then play the same game as with an emission line: look for where this
“cliff edge” appears in the observed spectrum and then use that observed
wavelength (which will be much longer than 91nm) to estimate the redshift.
Another clear explanation from Prof. Hendry, who never makes us teachers feel silly for asking questions. Thanks to Mr Thomson and his student for the original question.
Here I will post a few tips and hints to remember when answering SQA Higher Papers, hopefully they’ll be quick, snappy and memorable. You’ve got the whole of the Scottish Physics Teachers’ Community Wisdom Below!
How to remember Cosmic Microwave Background Radiation (spell the whole lot not CMBR, as this isn’t a name) However, the way to remember CuMBRia.
Conservation of Momentum IN THE ABSENCE OF EXTERNAL FORCES, MOMENTUM BEFORE THE COLLISION IS EQUAL TO THE MOMENTUM AFTER THE COLLISION.
Obviously you know- no secs in Physics, just stick to unit symbols and save all the problems of spelling.
Fundamental Particles: Key point: it is not that they can be used to make bigger ‘things’, but rather that they are not made from smaller things.
Strong force (associated with the gluon) acts over a very short distance.
The gravitational force extends over very large/infinite distances.
Neutrons don’t carry/have (net) charge so cannot be accelerated/guided/ deflected by magnetic fields.
Remember: SIG FIG, your final answer should be rounded up to the same number of significant figures as the LEAST significant measurement.
Don’t forget to revise your uncertainties.
Make sure you see the words “end of question paper”. Don’t assume you’ve got to the end and there are no questions on the very last page!
“Show” questions – means show correct formula, working and numerical answer stated as given in the question.
Don’t leave anything blank! If you really don’t know, give it a go – you never know.
The questions in the exam sections (MC and then extended answers) are in approximately the same order as the equation sheet.
LIST: given numbers with the correct symbols before doing a calculation. Or as we say IESSUU (information, Equation, Substitution, Solution, Units and Underline)
Substitute then rearrange.
Read all of the question, especially that bit you skipped over at the start.
Don’t forget units! It’s now worth at least 33% of a calculation!
This will do for now more to come as they arise……Check out the past paper marking instructions for do’s and don’ts- its full of them in that second column!
Here are some top tips for Revision from Mr Dawson from Wallace Hall Academy- thanks
What the 2017 results show is that they final result for the Assignment is mainly down to the way it is written up and not to do with intelligence or choice of topic.
A point light source will spreads its energy equally in all directions. Therefore if you wanted to find all of the points in space where the energy was of the same intensity you would have to draw a sphere around the source point. The bigger the radius of the sphere the greater the ‘surface’ over which the energy was spread.
The relationship between radius and sphere surface area is an inverse square relationship. That means that intensity will depend on 1/r2. If you double the distance from the source the intensity will not halve but drop to a quarter of its value, tripling the distance will make the intensity drop to a ninth and so on.
Point sources of other quantities also obey the inverse square law.
Please see the link below for the (relatively new) CERN summer residential programme for school pupils. To be eligible, they have to be 16 or over on 24th July 2018, and can either have another year of school ahead, or have just finished school. There are 30 places, it’s open to the whole world, and all costs are covered so I suspect it will be rather competitive(!) but perhaps worth a shot? Application deadline is 5th February:
Here are some more fantastic videos, which you generally can’t have access to in school so I’ve downloaded the videos for you. When at home please visit the original sources.
Dr Physics A is a fantastic communicator who makes all the content so accessible. He is working through the A level course and some of the content relates to A level material, and is done in a different manner to Higher and AH. The content isn’t wrong, it is just defined by different terms. Find his channel here.
Watch, if you check his equations for the special relativity topic he transposes t and t’ (as do many texts etc. Scotland always does things differently)! Check off each of the content points from the outcome booklet.
Here is a link to a fantastic little book that started me on my “very short introduction” library. It has been uploaded as a pdf file, but if you enjoy it give the author some credit and pay the guy (Russell Stannard) by buying it!
You should all try to make your holiday videos so useful in showing Physics ideas! Who is in motion? Does it remain the same throughout the sequence?
This is covered in the web-based research post but I’ve uploaded it here as an MP4 file.
Just check this off against the content as it isn’t all covered at Higher (some is the AH and some isn’t covered at all).
Neil deGrasse Tyson with his inimitable style explains the Michelson-Morley experiment and shows that despite getting a rubbish result it doesn’t say your results are rubbish! This was big Science progress and it wasn’t explained until Einstein came along. It was the turning point that transformed Science.
Here are further explanations of the Michelson-Morley experiment and a hint of more of the course to come.
Evidence for Special Relativity
Sixty symbols- Nottingham University
Sixty Symbols by Nottingham University are an amazing set of videos, although far more than sixty by now. Check out and keep watching.
…. and here at the end I have uploaded the worked answers (thanks to whoever wrote these excellent questions) so that you can check off your tutorials.
