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Practical Demonstrations

These videos have been filmed with teachers in mind, showing how you can use simple lab equipment to demonstrate concepts taught from KS3 to A Level. There are also some areas that are not on the syllabus which will interest students and can be understood if explained clearly.

Please make sure you carry out any necessary risk assessments for the equipment you use if you try any of these.

Who is this other teacher?

Mark Harrison teaches Physics at a school in Bath and is finding it difficult to believe that September 2017 marks the 20th anniversary of the start of his teaching career. He is building a website of all the useful bits of teaching advice and resources that he wishes had been available back then, everything being freely available at

Ribbon Tweeter

Ribbon tweeters are used in some loudspeaker designs (often big PA systems) to reproduce high frequency sounds accurately and simply. Wonderfully, you can build your own, using little more than a strip of Aluminium cooking foil, a strong magnet and a signal generator/amplifier: here, Mark shows you how.

TIR in Water

Total internal reflection is usually demonstrated and discussed in the context of solids, like light going from glass to air, the idea of optical fibres and so on. Here, though, Mark shows how TIR can easily happen in a stream of water. Remember to be careful with laser pointers in the classroom and follow your local risk assessments and advice.

Barkhausen Noise (Hearing Atoms Move)

Magnetic domain theory is a simple but powerful model which explains why many magnetic effects happen. Usually in schools, it’s presented to pupils entirely theoretically, but science teachers should always be keen to give experimental evidence in favour of what they teach. Here, Mark shows you how to do a simple demonstration to do just that, based on his 2011 paper in the journal Physics Education.


[Erratum: Barkhausen noise was discovered just after the First World War (in 1919), not just before as stated in the video]

The Curie Point

Building on the Barkhausen noise demonstration, this is another demonstration which gives evidence in favour of magnetic domain theory. If you try this yourself, do your own risk assessment, particularly for the hot wire which is easily enough to burn your skin.

Thermal Energy in Collisions

When teaching about energy and conservation of energy, you might have had to convince your pupils to believe you that objects and their surroundings heat up in collisions. Some of your pupils may have been less convinced than others. Here, Mark gives a wonderfully simple yet direct demonstration that it really does happen.

Series and Parallel Circuits

The equations for electrical power that many pupils come across in school might seem simple, but it is very easy to misuse them and end up with contradictions or other problems. This demonstration shows how you can get very different results from the same equipment just by changing one thing – knowing which Power equation to use in each case is the key to understanding what’s going on.

Five Dollar Diffraction

Several countries have started to put ingenious diffraction grating-style features into their ‘paper’ money. Here, Mark shows you what happens when you shine a laser through the right part of a Canadian $5 bill, whilst secretly being very glad that someone else had to solve the Bessel function necessary to yield this diffraction pattern.

Lissajous Figures

What’s more fun than 1-dimensional SHM? Why, 2-dimensional SHM, of course. Here Mark shows how to combine two signal generators and an oscilloscope to produce what are known as Lissajous figures, named after a 19th century French physicist. They are both practical and pretty: the Dadaist artist Max Ernst built an apparatus to make Lissajous figures using an oscillating cup of sand.

Botafumeiro Pendulum

If your first thought – not unreasonably – is ‘what on Earth is a botafumiero?’ then you might want to watch this first, especially from about 1:00 onwards. If the periodic pulling on the rope which starts in that video at 1:22 seems a bit odd, this video explains why. Mark has also written an explanation of this situation on his website, at

Laser Speakers

Very few pupils will be impressed that (electrical) sound signals can be sent down a wire, but sending it through thin air with a laser is much more attention-grabbing. Here, Mark shows how it can be done.

Why Microwave Polarisation is Wrong!

Polarisation has some lovely demonstrations associated with it. Here, Mark shows how some older kit can be used to show polarisation of microwaves in particular, and also how the very common ‘picket fence’ analogy for explaining polarisation needs to be handled with care.

Independence of Horizontal and Vertical Motion

Understanding that vertical and horizontal motion are completely independent of each other is a very powerful piece of knowledge for solving many mechanics questions. It’s not surprising that there are many well-known ways of using it in Physics teaching, like the Monkey and Hunter. Here, Mark shows a couple of other ways that pupils who are finding it difficult to believe that horizontal and vertical motion are definitely completely independent of each other might be convinced.

Making Liquid Oxygen

This is a quick demo you can carry out if you have access to liquid nitrogen. I show how you can set this up using simple lab equipment.

Very Cold Circuits

In addition to the normal frozen bananas, liquid nitrogen can also be used to show how resistance changes with temperature and the rate of chemical reactions.

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