Category Archives: Teaching

You must be on your holidays now

You must be on your holidays now? I’m confronted with this question/accusation every time I go shopping in my village these days. Almost everyone I know assumes that lecturers merely teach and the summer holidays are ours to enjoy at our leisure.

I never know how to correct this misapprehension. Usually, I just nod amiably – after all, the main thing is that I have a job I really enjoy doing. However, it worries me that there is such widespread misunderstanding of academia. Occasionally, I try to explain that ‘holiday-time’ is in fact the only time I get to do any research. However, I usually get the feeling the questioner either doesn’t believe me or thinks I’m a fool for not putting our generous holidays to good use.

And the official holidays are generous, there’s no question. In the Institutes of Technology, staff do not have to report formally for work from June 20th to September 1st. It sounds great, doesn’t it? But for those engaged in research at any level (and it’s very difficult to get a job teaching to degree or master’s level if you are not engaged in some sort of research), this is the only time such work gets done.

In my case, I used to head back to my alma mater Trinity College as soon as term ended, doing experimental work in the magnetic resonance lab. These days, I’m more involved in writing science. This summer, I’m working on a book on cosmology, aimed at a popular audience. I started it last summer at Harvard and have been tipping away whenever I can during a very busy semester. Now I have a good opportunity to finish. I don’t think of this as a chore; like most academics, I see this sort of work as an important part of my job and it’s very satisfying. I really like working in the college over the summer months, it’s a very nice environment of quiet academic activity.

I also have two conferences in August and next month I’m giving a public talk on Irish astronomy and the big bang. So it’ll be a busy summer, which doesn’t bother me in the slightest as long as I get away for the odd weekend. As for travel, I’m coming round to the view that most countries are simply too hot for me in the summer and I like the variability of Irish weather. I’ll take a few weekends in the west coast of Ireland, playing tunes in the pubs at night and surfing during the day, that’ll do nicely…

It’s a tough life – Ed


This blog has been nominated for an award, the Three Quarks Daily 2012 Awards. If you like the blog, why not throw in a vote here.  That said, there are some great blogs on the nominee page, I’m having fun browsing them all


Filed under Teaching, Third level

Exam corrections

I’ve just finished correcting the last exam script of summer 2012.  No more corrections until August, yipee. That said, I don’t really mind correcting the semester exams, unlike most of my colleagues. One reason is that I see it as a form of feedback, if pretty shocking sometimes!

Oh joy

It’s probably true that correcting maths or physics exams is somewhat easier than fighting your way through hundreds of poorly-written essays. (I suspect it’s also less depressing – I often think the standard of literacy amongst our students is more worrying than their lack of mathematical ability). By the time I have corrected the first ten physics scripts of any course, I have usually committed every possible answer to memory, so the job goes quite quickly. Also,  I like a task that has a definite beginning, middle and end with room for targets and treats along the way…

In our college, exam scripts are corrected by name and the students sometimes campaign for anonymous marking. Little do they know that from a teacher’s perspective, it’s much harder to fail a person than a number, particularly if you know that student made a decent effort during the semester. Indeed, a great deal of correction time goes into trying to trying to find a few extra marks for the borderliners; if anything, I would expect pass marks to drop if anonymous marking was introduced.

The main downside of examinations is the administration. Combining exam results with attendance and continuous assessment marks, and getting the totals to the department in time for the course board meetings is no trivial task if one is teaching several different courses . Worse, there are always one or two students who seem to have appeared out of nowhere, with an ensuing search for their educational record and assessment results.

By the end of this week, the innumerable departmental meetings will be over, and we will be ready to meet the externs next week. After all that, the results become official and I will finally, finally get back to research…


Filed under Teaching, Third level

A letter to the Minister for Education

On Friday evening, I gave a public talk on the big bang at Blackrock Castle in Cork. I always enjoy giving public science talks, but this one was special (slides here). The venue was a beautiful castle overlooking the sea and I was enormously impressed with the science outreach work being done there by Dr Niall Smith, director of research at Cork Institute of Technology. I was equally impressed with the new observatory at the castle and the astronomy program of Niall and his postgraduate students. Superb work in a fantastic location, surely an inspiration for generations of young students.

Blackrock Castle in Cork: the white dome above the tower is the observatory

I left Cork early on Saturday morning in order to travel to Dublin to catch the High Flyers conference of the Institute of Physics (this is what physicists get up to on bank holiday weekends!). On my way to the meeting, I heard the Irish Minister for Education interviewed on RTE Radio One (Marian Finucane show, May 5th). The Minister had many interesting things to say on subjects such as RTE, the Catholic Church, a recent libel case in Ireland and the near-paralysis of political process in the United States (the latter is a most unusual topic for a politician over here). However, I was taken aback to hear him refer to “problems of productivity in the third level sector, particularly in the Institutes of Technology”, and disappointed that the interviewer didn’t seek some clarification on the comment.

I would very much like to know what the Minister meant by this comment. What do we understand by ‘productivity’ in the context of the third level education? How is it measured? Is it the number of students taught? Number of Noble prizes for research?  Perhaps some Soviet-style quota of engineers graduated? Like all Institute lecturers, I have a heavy teaching load; we produce legions of exactly the sort of science, computing and engineering graduates that Ireland so desperately needs. I must say I grow weary of generalizations like this about third level academics from journalists and politicians, and such a comment from the top man in education is pretty serious. Not a scintilla of evidence was offered by the Minister in support of his remark, just a casually delivered public insult to my colleagues and I.

Here’s the thing, Minister Quinn: like almost all lecturers in the Institutes of Technology (IoTs), I teach between four and five different courses per semester to degree level, a larger teaching load than any third level college in the world as far as I know; add research and outreach activity to this and it is no surprise I am in the office until 9 pm at least four days a week. In terms of prep, each semester typically presents at least one new module to teach, involving months of preparation over the summer, where I would hope to be concentrating on research, finishing my book and attending conferences. (I teach diverse courses in mathematics and physics to students in the departments of computing, engineering and science, not to mention more specialized modules in quantum physics, cosmology and particle physics – how many Harvard professors can boast such a wide teaching portfolio?).

‘Yes, but what about other IoT lecturers?’, the Minister will ask. I imagine I have a more accurate view of the work of my colleagues than the Minister’s advisors and I have no complaints. Indeed, the limited time I have for research arises because other lecturers take on the bulk of student administration (the large number of classes in the IoTs necessitates a great deal of admin; Year Tutors and Course Leaders spend a great deal of time keeping track of attendance, assessments, lab performance  and exam results). There are no easy lecturing jobs.

I love my job and stopped counting the overtime years ago. However, it is frustrating to hear the work of lecturers in the institutes and the universities denigrated by politicians who know nothing of what we do. The tragedy is, I suspect the binary system of universities and institutes has served Ireland very well, although few in charge of education seem to realize it. As they consider the future of the third level sector, I hope politicians and their advisors will make an effort to understand the current system, rather than indulge in unsupported generalizations.


Filed under Astronomy, Teaching, Third level

Last day of semester

Today was the last day of lectures in the first semester, hurrah. There’s something very satisfying about emptying out the teaching briefcase and filing the notes and overheads back on the bookcase until next year. (Yes, we have computers and data projectors in Waterford, but I still use overheads quite a bit). The students now have a study week followed by exams but for lecturers, it’s an ideal time to get back to research.

I’m frequently asked if WIT is a let down after Harvard, but I must say I enjoyed this semester no end. I taught maths (to 1st science), physics (to 1st engineering) and my ‘concepts in cosmology’ course to our physics students. I’m writing a book based on the latter so it was fun summarizing a chapter each week and presenting it in class as bullet points. After each lecture, I found myself rushing back to the office to rewrite a paragraph or re-jig an explanation – very satisfying!

Motivated students

Then there was the neutrino experiment; a superb opportunity for public lectures on relativity. Like almost all physicists, I expect this result is an anomaly because neutrinos are known to have a finite rest mass. I really enjoy explaining this in outreach lectures so long may the anomaly survive! The Trinity lecture was very satisfying, we got a great crowd including some very eminent physicists.

Now I have four weeks to work quietly on the book, uninterrupted by classes – what a job!


Meanwhile, rumours continue to circulate in the media about a possible sighting of the Higgs boson. I haven’t heard anything in physics circles so I’m betting it’s a false alarm based on a misunderstanding of the purpose of next week’s roundup meeting at CERN (see here for more on the rumours). Still, I’ll be keeping an eye on the news on Tuesday!


Filed under Teaching, Third level

Back to school in Ireland

I finally left Harvard in the last week of August, having had a wonderful summer working quietly on The Book during the day and sailing on the Charles in the long summer evenings.

It’s nice to be back home too – no more going around in silly shorts, suncream and shades. Back at Waterford Institute of Technology in the southeast of Ireland, we are already in the second week of teaching term. The bad news is that thanks to the recession, teaching loads have been increased (increased productivity!) leaving almost no time at all for frivolous activities such as research. On the other hand, there is much discussion of the college being upgraded to full university status, mainly because the government thinks that an upgrade ay help attract industry to a region badly hit by the recession. So after all the valiant efforts of WIT researchers, it seems an upgrade may occur for political reasons…

How does the college seem after Harvard? Colleagues keep asking me this. Yes, I miss the beautiful Harvard campus, the incredible libraries and the superb seminars. However, the main day-to-day difference is one of organization. There seems to be a problem of chaotic timetabling in WIT for the first few weeks of every semester, at least in my department. It’s very stressful and leaves no time over for prep or research. I’ve never understood why this happens every year, as our staff and courses change relatively little. One reason might be that lecturers are left to decide who teaches what amongst themselves, pitting Alice against Bob. Give me a didactic Head of Department any day…

Waterford Institute of Technology

On the other hand, it’s great to be in a job with an influx of Hopeful Young People every year. I always think that academics are v lucky in this regard, it doesn’t really matter which college you are in. Another change is that I am moving to a smaller, quieter office yipee. There is a special place in hell reserved for managers who believe that academics work well in large open-plan offices. With students coming to the door and phones continually ringing, it’s impossible to get any work done between classes. Hopefully I’ll have some quiet evenings in my nice new office….


Filed under Teaching, Third level

Introductory physics: the lens

A spectacular application of the phenomenon of refraction (see previous post) is the lens. Just as a focusing mirror is used to obtain an image of a distant object (see post on mirrors), a lens is used to focus light by refraction. The difference is that the light is transmitted through a lens – it is refracted once entering the lens and again as it passes out again. Lenses are cut from parabolic surfaces in such a way that distant rays are brought to a focus at the focal point.

As with mirrors, there are two types of lenses, depending on the curvature of cut: a convex lens causes parallel rays of light to converge to a real focus, while a concave lens cause the light to appear to diverge from a virtual focus.

As with mirrors, the position of an image will depend on the distance of the object from the lens (but the image of a distant object will of course be at the focal point of the lens). Amazingly, the same equation applies: for an object a distance u from a lens of focal length f, the location v of the image can be found from the relation

1/u1/v =   1/f

(Note that for a distant object u = and hence v = f ). The magnification m of the image can be calcuated from the equation m =  –v/u, as before.


Lenses are used extensively in everyday life. The most common example is of course spectacles. No one knows when spectacles were first invented (12th century?), but they have been used throughout the ages to improve defective human eyesight.

Typically, spectacle lenses are concave (diverging) lenses are made from glass or plastic. This is because the most common eyesight defect is myopia (shortsightedness), a condition where the natural lens of the eye focuses too strongly i.e. an image is formed short of the retina. A diverging lens of the right strength placed in front of the eye will cause the image to be projected back on the retina as normal.

Concave (diverging) lens used to correct myopia

In the case of hyperopia (the longsightedness that occurs commonly in older people), the eye muscles are weakened and an image is formed beyond the retina; this is corrected by placing a convex (converging) lens in front of the eye in order to strengthen it i.e. shorten the focal length of the eye’s natural lens.

Converging lens used to correct longsightedness

A modern application is the contact lens: this operates on the same principle as above, but the lens is made of a soft fabric that can be worn directly on the pupil. A third option nowadays is laser surgery; in this case the focal length of the eye’s natural lens is adjusted directly (and permanently) by laser treatment.

Lenses and science

Lenses played a pivotal role in the development of science. In the 17th century, advances in lens technology led directly to the invention of the microscope, a device that revolutionized our view of the world of the very small: and to the development of the telescope, an invention that revolutionized our view of the solar system and ultimately the entire universe.


1. If an object 5 cm high is placed 30 cm in front of a convex (converging) lens of focal length 20 cm, calculate the position and height of the image.  Is the image real or virtual?

2. As a shortsighted person ages, can the onset of longsightedness cancel myopia?


Filed under Introductory physics, Teaching

Introductory physics: circuits

Electrical devices (TVs, stereos etc.) are connected to a voltage supply by an electrical circuit. The only difficult thing about circuits is that devices can be connected either in series or in parallel.

If connected in series, the same current runs through each device since there is no alternative path. However, the voltage across each device is different: from V = IR, the largest voltage drop will be across the largest resistance (just as the largest energy drop occurs across the largest waterfall in a river). As you might expect, the total resistance (or load) of the circuit is the sum of the individual resistances.

On the other hand, electrical devices can also be connected in parallel. In this case, each device is connected directly to the terminals of the voltage source and hence experiences the same voltage. Here, there will be a different current through each device since I = V/R. A counter-intuitive aspect of parallel circuits is that the total resistance of the circuit is lowered as you add in more devices (the physical reason is that you are increasing the number of alternate paths the current can take).

Parallel circuit: each device is connected directly to the battery terminals

Which is more useful? Household electrical devices are connected in parallel because it is easier (for the manufacturer) if every device sees the same voltage and it also turns out to be more efficient from the point of view of power consumption.

A more complicated type of circuit is the combination circuit: here some resistors are connected in series, others in parallel. In order to calculate the current through a given device, the trick is to replace any resistors in parallel with the equivalent resistance in series and analyse the resulting series circuit.

Combination circuit


Assuming a resistance of 100 Ohms for each of the resistors in the combination circuit above, calculate the current through each if a voltage of 12 V is applied.


Filed under Introductory physics, Teaching