Physics

What do you do when Science equipment breaks down?

Question:
How do you tell Biology from Chemistry from Physics?
Answer:
It it wiggles it’s Biology, if it smells it’s Chemistry and if it doesn’t work it’s Physics.

I don’t know of any teacher-training course which spends time training teachers on the finer points of being a technician. Yet when equipment does break down you’re expected to somehow just ‘know’ what to look for – and how to fix it.

Even better, if you’re the Physics teacher then you automatically become the ‘go-to’ guy (or gal) for colleagues (and not just Science colleagues) when they have something which needs fixing.
If you’re replacing somebody who just retired then the chances are good that this person is not going to come back in to help you become familiar with what does and doesn’t work. It’s quite possible that you’ve never even met this person, so you’re likely to spend the next few years finding pieces of apparatus in shelves without having any clue as to what their function is.
As a result the shelves in our labs are full of expensive equipment that just sits there gathering dust.

So what do you do when something breaks down?
One option which many are not aware of is to ring up your supplier of school science equipment and ask them if they can fix it. Many of them do have repair departments and should be able to give you a quote which you can then compare to the price of a replacement.
Another option is to ask a senior class if anybody there wants to have a look at it. Usually you will find somebody there who has more free time than you do (but obviously don’t allow them play with anything that could have health and safety implications).

My contribution to Science Week – I thought I might teach some physics

At 40 mins long it’s not going to go viral anytime soon. It’s the middle 40 minutes of a double class but in it we managed to learn about some of the following:

The structure of the atom.

We, and everything around us, are mostly empty space.

We discovered that the appearance of  ‘solidness’ is an illusion – which lead to a  discussion about how light works.
We learned that there is a cultural aspect to what we see (and you definitely won’t find that in physics textbooks) and that Newton himself was subject to this and it resulted in him making a boo-boo that still goes uncorrected right up to today.

We discovered that electrons are constantly cascading down along everything we see in a seemingly never-ending avalanche, powered by energy from incoming light (so when this power source disappears, the electrons no longer have energy to jump up or fall back down, otherwise known as darkness).

We learned why things feel solid – all to do with the force of repulsion between electrons at the surface.

We developed a deeper understanding of Newton’s Third Law.

We discussed the fallacy of language – know the word for something (like gravity) and understanding what gravity actually is are two very different things, and shouldn’t be confused with each other.

We discovered that physics teachers don’t have all the answers, and should never pretend otherwise.

We were reminded that because almost none of the above is in the syllabus, the syllabus is a disgrace. It’s no wonder students don’t see the point of it.
There were 22 students in that class and the discussion could have gone on and on – I had to kick them out the door.  One can only imagine the conversations they must have had over the dinner table that evening.

If only all those who make such a fuss over Science Week could put a fraction of that effort into making the school syllabus a source of wonder and curiosity instead of what it is – a series of dull as dishwater facts which are to be merely learned off by heart.

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!

Leaving Cert Physics notes updated

This blog has been fairly quiet recently; I have spent every spare minute updating the student notes on the website and feel very proud of my work. I don’t know if anyone else is going to notice mind, but then I guess that’s not the point.

For each chapter I have included all past exam questions, which can be cross-referenced with the relavant marking-scheme which is also included. Also included is  a copy of the associated extracts from the syllabus – this gives the students the responsibility of checking up on me to ensure I have everything covered before moving on to the next chapter.

There is also plenty of “extra-credit” material tucked in at the end to help address many of the conceptual difficulties which students (and teachers!)  have; these also help to set the historical and social context of many of the discoveries. Science is after all a very human activity, dispite what you might think from the text-books and syllabus.

I would hope that students outside of my own school would find these useful, particulary those who don’t have a specialised Physics teacher should find it to be a useful resourse to help them help themselves.

Some would see the decision to allow the students to see their test in advance to be somehow ‘cheating’, but for me it helps overcome one of the biggest obstacles facing many students who may not be in the top bracket; they simply don’t know what to learn. I have found with this new approach that hard-working students who are of average ability have gone from 50% to 75% since I introduced the option. It doesn’t change those at the top; the A-students still get their A’s, while at the other end those determined to do as little as possible still continue to achieve results which reflect this.

But I’m delighted with this practice. We spend at least one class and maybe two going over these questions at the end of each chapter and before I give them the test. Then I simply pick ten questions from the list, while altering the numbers in the maths questions. After seven years of leaving-cert questions (2002 – 2009) there is a pretty comprehensive bank of questions there, so I don’t believe it is giving students an inflated sense of their own worth.

But as an incentive to prepare for class tests and greater student participation it is working like a dream. I’m not too proud to say that I’m thrilled with my work!

Colours from black and white? Say it ain’t so!

We had half a class the other day so we just played around with some equipment left lying about.

One such piece was a cardboard disc with black circles and shapes on a white background. If you spin it quickly you get to see coloured circles! It’s mad I tell you.

Only thing is, because it’s got to be a psychological effect it doesn’t get picked up on the camera.

Hates that.

Unusual resource for explaining Joule’s Law

An offshoot of Joules’ Law is that when transmitting electrical power, the current is kept as low as  possible in order to reduce energy losses associated with heat of the electrical cables. Because the power being transferred is the product of the voltage and the current, we can still get the same power transferred if we halve the current and double the voltage, or; make the current very, very small and make the voltage very, very big.

So power -lines transmit power at a voltage of up to 400,000 volts. Then, as the power gets closer to the home, the voltage is reduced in stages, and correspondingly the current gets increased. This occurs in appiances called transformers.

I came across a lovely interactive explanation of this when in honeymoon in Hong Kong.
I couldn’t resist.