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).

Just so you know, nobody knows what energy is

The following acts as my introduction to the students’ notes on the Energy chapter.

What is energy?

Nobody knows what energy actually is and by pretending otherwise we actually do you the student a disservice. Not only are we ignoring the wonder associated with the idea, we are also denying you the opportunity to engage with the concept at any level beyond the superficial.

Bottom line; nobody gets energy because there’s nothing to get. Energy is not tangible (it is ‘an indirectly observed quantity’); you can’t hold it in your hand, you can’t weigh it on an electronic balance, you can’t see it, touch it, smell it etc. Yet when the universe was first created there was a certain amount of this put in to the mix (actually now that I think about it the mix itself was energy (with perhaps just a little dash of time)), and it’s all still there today. Its form can change, but the energy itself can’t ever disappear – no sirree bob.

It could be argued that it is in fact merely an accountant’s trick which enables him to ensure that all actions balance.

Consider the following analogy which I like to use.

If a child asks you ‘what is money?’ you could take a few coins out of your pocket and show them to the child and say ‘this in money’. Now fast forward a couple of decades; all transactions are now done electronically/online and all coins and paper money are no longer legal tender. Now how do you explain what money is?

Well it’s a means of payment for goods and services, right? Somebody sells you an orange and you agree to transfer into their account a set amount of this ‘money’. And now that the shopkeeper has this money in his account he can use it to buy something else. So in effect money is just a transferrable IOU.

Now energy is a bit like this, but there is only a certain amount of IOU’s in the universe and this was set when the universe first came into being.

To complicate matters further, since the early part of the last century we now know (thank you Albert) that all matter (‘stuff’) is basically energy in another form.

Anyone still with me?

 

All right, let’s listen to Richard Feynman give his take on it.

There is a fact, or if you wish, a law governing all natural phenomena that are known to date. There is no known exception to this law – it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call “energy,” that does not change in the manifold changes that nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says there is a numerical quantity which does not change when something happens . . . it is a strange fact that when we calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same. It is important to realize that in physics today, we have no knowledge of what energy “is.” We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. It . . . does not tell us the mechanism or the reason for the various formulas.

The Feynman Lectures on Physics Vol I, p 4-1

When Feynman wrote,
“It is important to realize that in physics today, we have no knowledge of what energy is,” he was recognizing that although we have expressions for various forms of energy (kinetic, heat, electrical, light, sound etc) we seem to have no idea of what the all-encompassing notion of “energy” is.

The various forms of energy (½mv2, mgh, ½kx2, qV,mcT, ½I2, ½CV2, etc.) are abstractions not directly observable.

2007 American Association of Physics Teachers

Now with that interesting bit out of the way, let’s go see what we need to know for the exam.

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Some wonderful demonstrations using an inexpensive pressure pump

Available for about €20 from amazon.co.uk

I’m thinking of getting about 8 to act as a class set, and a few more for presents to nephews and nieces.

The ‘Presssure and Sound’ demo can be done with mobile phones as I suggest – the sound level does drop noticealbly in the classroom, but not enough to be picked up by the camcorder.

I presume it would also go down well on Open Day.

Limitless potential.
Eoghan in Second Year suggested using coke to see if it goes flat – I won’t tell you the answer but it’s worth checking out. In hindsight we should have tried to guess what we would have observed.

Then we wondered if the pH would change.

Then we wondered if the level of Carbon Dioxide in the chamber would increase noticealby, even as we pumped out the air. I need to see if we can use a datalogger to see how the  concentration of the gas changes in real time on a laptop.

Then I mentioned that we need to buy lots of marshmallows to see which work the best.

Then Robyn said that she cooks marshmallows at home, so now she has promised to bring in the ingredients and we will try to cook them in school and see if we can make giant ones!

All for €20 plus the price of few marshmallows, balloons and shaving foam.


Is it a particle or is it a wave?
Sometimes I think I’d gladly be locked up in a dungeon ten fathoms below ground, if in return I could find out one thing: What is light?
Galileo, from the play Life of Galileo, by Bertolt Brecht

 The single greatest source of debate among physicists in the early decades of the last century was to do with the nature of light. Come to think of it, this concept has probably caused more angst than any other to scientists and philosophers right back to the ancient Greeks.
To take just one aspect; we can prove that light is a particle (via the photoelectric effect) and we can prove that light is a wave (via interference, or the famous ‘double slit’ experiment) yet particles and waves are two completely different phenomena. Particles are ‘things’ and are therefore supposed to be localised in space and have mass. And while there are  different varieties of waves, they are not supposed to be ‘in one place’ or have mass.
So what gives?


 

Answer: nobody knows. To this day there are different interpretations, but none that is accepted by all. The YouTube clip below shows some of the world’s greatest physicists coming together for one of a series of conferences to try to make sense of it all back in the 1920’s. Needless to say they did not reach a consensus. There is wonderful book called QUANTUM which describes in great detail the history of this debate at the beginning of the last century. See here  for a previous post on the book itself.

Now in leaving cert physics we need to know the evidence for light being both a particle and a wave. But there is room in the syllabus or any of the textbooks that I have come across to highlight the bizarre nature of this. It lies at the heart of one of the greatest problems scientists have ever faced, and our response is to simply pretend that there is nothing of note here.

It’s simply not good enough.

Ernst Mach: the problem with Science Education

mach

1859 marks not only the 150th birthday of the publication of Darwin’s On the Origin of Species, but also a somewhat less well-known occasion; It was the year Ernst Mach published the first of his 500 publications (his last was published five years after his death, in 1921).

Most will know of this man through his association with the speed of planes;  Mach Number is the speed at which an object is moving divided by the speed of sound.

But Mach has offered much more to the world of Science; he lived in a time when Philosophy and Science went hand and hand, and he made many contributions not just in these areas, but also in Psychology and Educational Theory. He wrote a number of text-books for school science, but was very critical of the tendency of cramming as much as possible into the syllabus.
This quote sums up so much of what is wrong with our schooling: 

I know nothing more terrible than the poor creatures who have learned too much . . . What they have acquired is a spider’s web of thoughts too weak to furnish sure supports, but complicated enough to produce confusion.

Mach was also an advocate of what are known as ‘thought experiments’, these later became famous through Albert Einstein and his idea of sitting on top of a light beam.  Indeed Einstein went on to give credit to Mach for his ‘philosophical writings’.  It’s probably no coincidence that Einstein’s views on education were not that dissimilar to Mach’s:

One had to cram all this stuff into one’s mind for the examinations, whether one liked it or not. This coercion had such a deterring effect on me that, after I had passed the final examination, I found the consideration of any scientific problems distasteful to me for an entire year.

Of course this was all over one hundred years ago. Obviously it’s all changed since then.
It would appear that we have some explaining to do.

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.

Free Telescopes for Schools – what a wonderful idea!

year_of_astronomy_2_thumbnail

A colleague reminded me recently that when you think about it, there are really only two concepts that fascinate young kids; Space and Dinosaurs.
Okay, so this is a gross generalisation, but with work with me here.

Somebody in England has cottoned on to the first part of this.

The Society for Popular Astronomy (SPA), Royal Astronomical Society (RAS) and Science and Technology Facilities Council (STFC) have teamed up to give free telescopes to 1000 secondary schools.

And in Ireland?
Don’t hold your breath.
But at least both of these topics are on the school syllabus right – especially seen as we seem to want to encourage more young un’s to take up Science?

Welllll . . . Umm . . . Ehhh . . .Hmmmm . . .

Too obvious I suppose.