From the Institute of Physics and the National STEM Learning Centre and Network (https://www.stem.org.uk/), this video is aimed at teachers and shows how to get the best out of a Van de Graaff generator. In the video, Michael de Podesta explains how the generator works and gives some tips on getting consistently good results when using the apparatus. The video concludes with a simple but effective demonstration of charge.
This is a 2 week low safety risk, high engagement, creative, design, build, inquiry-based and presentation activity that involves students in developing a thorough understanding of current electricity and how to apply that to electrical circuits in a meaningful and fun way.
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Thanks for the ideas Otto!
You probably know that voltaic batteries come in all kinds of shapes and sizes, from tiny button batteries to car batteries to huge industrial heavy-weights. They turn chemical energy into the electrical energy that people use to power clocks, toys, cell phones, medical devices, tablets, cars, satellites… and an LED! These batteries seem pretty complicated but you can make a real voltaic battery right in your kitchen. Grab the ice tray and start the electrons moving. Continue reading
Measuring tiny volumes with precision and accuracy requires a micropipet. In the biology lab, micropipets are used for preparing and loading DNA samples, microscale experiments and the preparation of many types of samples. These applications rely on good technique to reduce error. This guide explains how to choose the proper micropipet for the application and techniques to help ensure that measurements are accurate and precise.
Hans Christian Oersted (1777–1851), a Danish physicist, was performing an experiment in 1820 when he noticed that whenever an electric current from a battery was switched on or off, a nearby compass needle was deflected. Through additional experiments, Oersted was able to demonstrate the link between electricity and magnetism. The following year, English scientist Michael Faraday (1791–1867) created a device that produced “electromagnetic rotation.” This device is known as a homopolar motor since the motor requires no commutator to reverse the current.
A motor converts electrical energy to mechanical energy. The simple motor in this activity changes the electrical energy output by the battery to mechanical energy as the copper wire is set into rotational motion. Any current-carrying wire produces an associated magnetic field. The electrons in the wire are subjected to a magnetic field and experience a force—referred to as the Lorentz force—that is perpendicular to both the magnetic field and the direction of movement. At some point along the length of the wire, the electrical current is not parallel to the magnetic field. The resulting Lorentz force is tangential and induces a torque on the copper wire. This torque causes the copper wire to spin.
When charge moves, we call it electric current, but the word current is usually reserved for things like water flows. Does electric current really work like that? Electrons are quantum particles, so we have to be careful.