PP4SS Exhibits
Electrons and Magnets |
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There are two principle physical properties which underpin all of the PP4SS exhibits, and which are introduced here, in this first exhibit:
As seen in the picture above, a CCTV monitor (displaying images generated by two webcams) is used to display a monochrome image on the surface of the cathode ray tube. This is used to help describe the formation of a cloud of electrons within the heating element of the tube, their acceleration to high speed through an electric field towards the front of the monitor, and their deflection and distribution onto the phosphorescent display by means of magnetic fields. To illustrate the point further, and to let pupils carry out some experimental work, magnets are supplied (the toroidal one is shown above), which let the pupils experience directly the way in which a magnetic field will deflect the path of charged particles. (The pupils are all told not to try this out on colour CRT televisions, as it would permanently damage the registration of the three colour beams. And in today's litigious society...) |
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A simple (and provisional) worksheet (in Word format), used to take pupils through these steps, can be downloaded by clicking here. As an aside, it's interesting to think that there will be pupils who have never seen a television or computer monitor driven by a cathode ray tube, in which case this exhibit carries some historical significance! |
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