Electrostatics
Static electricity is great for grabbing students' attention, especially when the Van de Graaff generator comes out! This list pulls together some classic activities, and some new ones with a twist, to investigate electrostatics;
• separation of positive or negative charges when objects are rubbed together: transfer of electrons, forces between charged objects
• the idea of electric field, forces acting across the space between objects not in contact.
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.
Demonstrating Physics: Electrostatics
In this programme, from Teachers TV, David Richardson from the Institute of Physics continues with more physics experiments for the staff at St. James Catholic High School in London. Head of biology Wendy Butler has always been afraid of using the Van de Graaff Generator. David shows her how to use it dramatically and safely. We then see her demonstrate it to her year eleven group. David also shows some other striking experiments, including using a microwave oven to light a light bulb.
Van de Graaff Generator
This second film about the Van de Graaff generator is also very good. Not only does it explain clearly how it works, it also shows one of the very best Van de Graaff demonstrations – the flying cake cases. It’s really simple but very effective at illustrating the concept of electrical repulsion so start collecting those aluminium cake cases now! The cases that mince pies are sold in are ideal but if it’s not near Christmas you can use the internet to find a supplier.
Having seen the demonstration, and after picking up the cake cases from all over the floor, students should be able to explain what causes them to fly off.
Electric Sausage
If your school doesn’t have a Van de Graaff generator there are still lots of exciting demonstrations and experiments you can do on the topic of static electricity. This short film shows how to use a balloon to pick up paper (and explains how it happens). This is an experiment that the whole class can participate in. A similar experiment with a sausage is probably best as a teacher demonstration but definitely worth doing. A set of teacher notes is also available to download but it’s pretty well all covered in the film.
Other experiments that students can do with a charged balloon include:
Deflecting a stream of water. Turn on a tap until there is a thin but steady stream of water flowing. Now move the charged balloon towards the water (but don’t touch the water) and watch the water move.
Moving a drinks can. Empty aluminium drinks cans are light enough (like the paper scraps) to be moved by a charged balloon. Hold the balloon over a can that is lying on its side. As the balloon is slowly moved, the can will follow.
Flying Tinsel
Physics is for life, not just for Christmas. This Christmas themed experiment would make a great practical for the last week of the autumn term but is also suitable for any time of the year. It follows on very well from the work with balloons detailed above but takes the ideas a bit further.
Forces due to electric charges
The first three experiments with balloons in this plan from the Institute of Physics are simple to carry out and very clearly show repulsive and attractive forces. They would make a good whole class demonstration during which questioning from the teacher could assess how much the students already know and challenge any misconceptions.
The second three experiments require the use of an EHT power supply (EHT stands for extra high tension and tension just means voltage), but these are probably best left until the students are older.
Be sure to read the very helpful teaching notes given towards the bottom of the page. Those teaching outside of their specialism will also find it worthwhile to read the related guidance on electrostatics. There’s a link right at the bottom of the page.