Leaving Cert Physics exam – final advice

Looking for a top grade?

Just one day to go.

Wondering what topics to concentrate on?

Consider the following:

Electromagnetic Induction has appeared on past exam papers on the following years:

2011 —

2010 —

2009 —

2008 no.8

2007 12 (c)

2006 no.11 {5/8 of a long question}

2005 12 (b)

2004 12 (c)

2003 12 (d)

2002 12 (c)

That’s right – it’s appeared every year from 2002 to 2008 but not for the last 3 years – don’t go into the exam without knowing it back to front and upside down. The document which contains all past questions on this topic together with the worked solutions can be found on the revision page of thephysicsteacher.ie.

How about The Electron?
Let’s take a look:

2011 —

2010 no.9

2009 no.8

2008 no.11{5/8 of a long question}

2007 —

2006 12 (d)

2005 12 (d)

2004 no.9

2003 no.9

2002 no.9

So most years it’s a full question, but hasn’t appeared last year at all. Same advice therefore – see all questions and solutions on the revision page of the website.

Particle Physics comes up every year – this year was the 75th anniversary of the Cockroft and Walton experiment – pay particular attention to past questions on this topic.

In fact for a full overview of all questions likely to appear this year (tomorrow!) you could do worse than check out the following:

If you want to download this document then the link is here

And remember – expect the unexpected. If something comes up that you haven’t seen before then just deal with it. Welcome to the real world!

And good luck with it 🙂

The nature of matter

Few concepts in Physics generate wonder quite like Quantum Theory. You only need to look at the shelves in the Popular Science section of a bookstore for evidence. Yet (once again) in schools we play down this sense of wonder. I used to think this wasn’t done deliberately but now I’m beginning to learn that there was once a school of thought that believed in doing exactly that, particularly for Science (more on that later).

Anyways, one of the most incredible ideas in Quantum Theory concerns the nature of matter itself – is it a particle or is it a wave?
For light, we can prove that it’s both (ridiculous though that may sound) and indeed students are expected to know the demonstrations which verify both. There is however no suggestion anywhere in either the textbooks (that I have come across) or in the syllabus that there is anything slightly disturbing in this. There was a single question on the exam paper once which asked why was Quantum Theory considered revolutionary, but that was it. No other reference to what is one of the greatest mysteries of science; how can something be both a particle and a wave. Why do I seem to be the only one who feels so frustrated by this?

So in an attempt to pass on some of this sense of wonder for the microscopic world, I put together the following set of demonstrations for my sixth years on the last day of term. It’s about 22 minutes long so is in two parts. Forgive its amateur appearance.

JC Science: Guide to Revising

A big problem with students who wish to do well in their exams is that they simply don’t know how much they have to know!

It’s a perfectly understandable complaint, and hopefully this will help.

Remember that for each chapter you will have to know:

  1. All definitions (see the notes I hand out in class)
  2. All experiments (whether mandatory or not)
  3. All maths problems (see separate guide to answering maths problems).
  4. Graph questions (see separate guide to answering graph questions).
  5. Any other theory

Get your friend/Mom/Dad/brother/sister to ask you the exam questions from the questions at the end of each chapter in my notes – all the solutions are there to check with.

When revising the Experiment questions don’t waste time writing them out fully. Sketch a quick diagram labelling all the main parts, and then write down one or two sentences summarising what you did.

You can go into more detail in the exam itself – this is just to check whether or not you can remember the experiment.

Get into the habit of marking/highlighting what you don’t understand, and then either ask a friend to explain it to you, or ask me.

Make sure you don’t leave it and hope that it won’t come up in the exam!

Most students who get A-grades in the Leaving Cert do this a lot. I don’t think it’s just a coincidence!

Try to revise one chapter of science per night.

BTW, this took time to put together so don’t be afraid to say thank you; you would be surprised how much a few small words could be appreciated (by all teachers, not just me!).

Good luck!

How to get 100% in your leaving cert Physics exam. Part 3: Short Questions

Question 5 on the paper is 56 marks and counts for 14% of the overall mark. The choice is to do 8 questions out of 10. It is one of the more popular questions on the paper.

I have compiled a list of all the short questions which have been asked over the last ten years,  together with their solutions. It is a detailed document (26 pages) but is worth knowing not only because it prepares you for Question 5, but also because it provides a comprehensive overview of all the topics on the course itself.
I have included the years with the questions because it helps to identify the questions which are particularly popular with the examiners.
e.g.

State The Principle of Conservation of Momentum.
[2002][2009 OL][2008 OL][2007 OL][2005 OL][2004 OL]
In any interaction between two objects, the total momentum before the interaction is equal to the total momentum after the collision, provided no external forces act.

And to my mind the two most popular questions at higher level:

What is the Doppler effect?
[2008] [2007] [2006] [2003] [2002]
The Doppler Effect is the apparent change in frequency due to relative motion between source and observer.

Define electric field strength.
[2009][2007] [2005] [2003] [2002]
Electric field strength is defined as force per unit charge.

There are a lot there so don’t try to learn them all at once; take a couple of pages each day, but then make sure you keep going over them (from the beginning each time) and in no time you’re confidence will be sky high!

Try to print two pages onto one sheet, and also back to back if possible to save paper.

How to get an A in Applied Maths

It may not seem a big deal, but if you’re a teacher of Applied Maths then worked solutions – whether they be Department of Education marking schemes or full solutions – can be a life-saver.

The official marking schemes go back to 1995 but for some reason you can only get back to 2001 on the Department’s site examinations.ie.

Over the course of the last couple of weeks one of my first-year Science students has been diligently giving up his lunch-times to scan in these earlier marking schemes which are not online (from 2000 – 1995), along with full solutions to 1994 and 1993.

These are all now available on the Applied Maths solutions page which is here.

Together with the existing older scanned in solutions it now forms almost a complete set of solutions going back 35 years.

Over the last couple of years I have converted the exam questions for all of these into Word format and these can be accessed here.

Alternatively I have incorporated the questions into a series of booklets (one per topic) where the questions are grouped by similarity. These booklets also contain introductions to the topics plus gradual lead-in questions taken from Ordinary Level papers.
Many of the questions have a ‘how-to-solve’ guide which gives you some help in answering the question without giving you the full solution (the full solution is available elsewhere).

As always, you can download these one document at a time or alternatively just send me a memory stick and I’ll copy them on and post them back.

Oh – and thanks to Eoin Robinson for all his help; If the resource is useful you might leave a comment and thank him!

Junior Cert Science: Unusual demonstration of magnetic fields

This week we looked at a concept called ferromagnetism which allows us to demonstrate the 3-dimensional nature of magnetic fields.

Thanks to my first years for being so co-operative 🙂

Here’s another way of illustrating the idea (which we didn’t do)

How to get an A in Junior Cert Science: Part 2 – the graphs

Since this science course was first examined in 2006 graph questions have become quite common.

There are different types of graph questions, and we will look at each of these different types in turn.

There is nothing scary here, and you have probably covered them all in maths anyway. It’s just that the science textbooks don’t seem to do a very good job of telling us why we have them in the first place, or why there are different types.

Why do we have graphs?

You won’t get asked this so you don’t have to learn it off by heart – I just thought you deserved to know.

There are many different reasons, but we’ll just look at two here.

Reason 1:

To see what the relationship is between two variables, e.g. between the extension of a string and the force which caused it.

Now assuming that a bigger force causes a bigger extension, the question is; are the two quantities directly proportional? i.e. if the size of the force doubles then the extension should be twice as much, if the force triples the extension will be three times as much etc.

Another way of saying this is that the two quantities increase at the same rate (as force is increased the extension increases at the same rate).

Or finally the scientific way of saying this is to say that the two quantities are directly proportional to each other (you must learn the phrase in italics off by heart because it gets asked a lot as you will see below).

To investigate this you would plot the results on a graph, and if the two quantities are directly proportional then you will find that if you draw a line through the points you will end up with a straight line through the origin (the origin is the (0,0) mark).

 

Reason 2:

In some graphs the slope of the line gives us some extra information (and you must know what this is).

There are only three graphs which fall into this category so make sure that you know each of them.

1. The slope of a distance-time graph corresponds to the speed (or velocity) of the moving object

2. The slope of a velocity-time graph corresponds to the acceleration  of the moving object

3. The slope of a voltage-current graph corresponds to the resistance of the resistor under investigation.

 

Note that for each of these graphs you will also get a straight line going through the origin, which verifies that the two quantities are directly proportional to each other.

 

Which brings us to our next problem – how do we calculate the slope of a line?

 

To calculate the slope of a line

Pick any two points (from the graph) and label one point (x1y1) and the second point (x2y2).

Make life easy for yourself by picking (0,0) as one of the points (assuming the line goes through the origin).

You must then use the formula:                                    

slope = (y2 – y1)/(x2 – x1)

Note that you can also find this formula on page 18 of the new log tables

Yo – Which axis is the y-axis?

Remember the yo-yo? It goes up and down right? Well so does the y axis (and it begins at zero) so y-zero = yo

Now that’s just freaky.

We are empty space

Having to pick out the singular most incredible concept in physics would be an interesting task (to say the least). Rarely a day goes by without me invoking the term ‘awesome’ in some context or other. I really do have a wonderful job.

Today however I came to what I think may be my favourite – the structure of the atom. You see the concept of solidity is merely an illusion. That table appears to be solid but actually it is 99.9999999% empty space.

“But it looks solid!”
Yup – but that’s (just) an optical illlusion caused by the interaction of electrons and incoming electromagnetic radiation.

“But it feels solid – when I bang my hand off the table I feel a solid surface!”
Again an illusion I’m afraid. This time caused by the interaction between electrons in your hand and electrons on the surface of the table repelling each other.

So next time you’re sitting in your car holding on to the steering wheel, just remind yourself that the steering wheel is hardly even there – neither is the car and for that matter neither are you (I’m trying not to have an exclamation mark at the end of every sentence here, but it’s not easy).

Now there is a (very, very) small amout of ‘matter’ in you. And here’s the thing; if you somehow managed to remove all the empty space in your body you would be left with a lump of solid matter which would be smaller in size than a grain of salt. How much would it weigh you ask? Why the very same as you do now, after all we have only removed the empty space (having a real tussle with the exclamation mark key here).

Okay, but this is all theoretical right?
Well maybe. It’s theoretical for humans, but there are objects out there which do not have empty space in them and which therefore are incredibly dense. They’re called neutron stars and to quote from Wikipedia:

this density is approximately equivalent to the mass of the entire human population compressed to the size of a sugar cube.

This gives them some other unusual properties. The radius of a typical neutron star is about 12 km, and just like a pirouetting ice-skater whose rate of rotation increases as they draw their arms in, so also does the rotation of a neutron star increase as its radius decreases. So how long does a full rotation last (remember that on Earth this is 24 hours)? On average there are somewhere between 100 and 1000 full rotations per second (see, if I can’t use exclamation marks at least I can use italics).

But back to the atom. To help students appreciate that it’s not just me who is bonkers, here I invoke the assistance of some more well-renowned experts.

Professon Brian Cox

Note that it took Rutherford two years to arrive at a correct interpretation of these results. It’s not like what you see in the textbooks – describe the experiment and then form an obvious conclusion.

It kinda freaked him out – Neil de Grass Tyson (audio link)

And for a bunch of other links see the related page on my website.

And finally, while you are expected to know that the atom is mostly empty (and be familiar with the experiment that ‘proved’ it), there is no sense in either the syllabus or any textbook I have come across of the wonder associated with this crazy idea. In fact it’s normally presented as just another piece of information to be learned off my heart. And I never hear anybody giving out about this, so I save my rants for unfortunate students and the odd blog post like this.

Now that’s mad!!

How to get an A in Junior Cert Science: Part 1 – the maths bits

Many students are turned off Physics because of the maths involved, yet you only need to be able to do ordinary level maths in order to answer all questions which will appear on the Junior Cert paper.

Some of these are in the new log-tables, but others are not so you should really try to remember all of them because it not always easy to identify the formula you need from the list in the log-tables. Practice looking for them in pages 51 – 56.

To encourage students not to give up on these questions I have put together a document which includes all the equations on the Junior Cert Science syllabus. There are (only) ten of them and by-in-large they are very straightforward. The document includes every maths question that was ever asked on a Higher Level or Ordinary Level paper from when the syllabus was first examined in 2006 up until 2010. It also contains solutions to all these questions.

If you’re looking for a top grade in June you really should ensure that you’re familiar with all of these.

You can download this document here.

There’s also a section on Units (we tend to be a little fanatical about these in Physics) and finally a list of practice questions.

If you’re using this as a teacher it should make a nice revision class or two – good luck with it!