the world in a different light
This is an interesting question on electricity: in order to survive a lightning strike, which of the following costumes offer the best protection? A coat of armour, your birthday suit, a wetsuit or a superman costume? Watch this MinuteEarth video on Faraday’s cage to find out!
I enjoy lecturing on topics like Superposition and Electromagnetism in the GCE A-level syllabus as they lend themselves well to the use of fun demonstrations that I can perform in front of the audience.
One of the recent demonstrations that I did was to demonstrate the measurement of the magnetic force acting on a wire and to show that the force can be inverted when the current is reversed. The magnitude of the force can be shown to be consistent with the relationship $$F = BIl \sin \theta$$, where $B$ is the magnetic flux density, $I$ is the current within the wire, $l$ is the length of the wire and $\theta$ is the angle between the wire and the magnetic field. This can be illustrated by independently varying one of the 4 variables and observing the change in force.
The setup is also a good for a demonstration to illustrate Fleming’s Left-Hand Rule.
Meanwhile, here’s a video I made to show what I did:
It’s about time Singapore considered building a liquid fluoride thorium reactor as a safe source of nuclear energy. From the video, it would appear that thorium is safe as it cannot be weaponized, does not require high pressure containers and the risk of a meltdown does not exist. For a small island state like Singapore, this presents an attractive way of obtaining relatively clean abundant energy. I’m sure if we think hard enough we will be able to solve the other problems such as storage of waste products.
Perhaps the part of our syllabus on Nuclear Physics will need to be updated then.
This video is taken during my IP4 class today. My students are making use of rubber tubes to demonstrate how we can use gravity to siphon water from one place to another. As long as the level of the source is higher than the level of the receiving end, we can do so.
This question is meant for TA 2B and 2C Physics students.
Other than the demonstrations we have tried out during class, could you think of any other way in which static electricity can be observed?
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Here are two applets students may like to try:
A. The first is a simple “experiment” showing that the extension of a spring is proportional to the force applied:
http://www.absorblearning.com/media/attachment.action?quick=5l&att=394
B. For the second applet, you can try:
http://phet.colorado.edu/sims/mass-spring-lab/mass-spring-lab_en.html