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Field Theory

How do electrons in a circuit know what to do?

Chris Meyer, Past President, Ontario Association of Physics Teachers

At times electrons can seem awfully clever, as if they talk to one another and plan what each will do: “okay, so you two go along that path and I'll go along this one” or “I'll only give up ¼ of my energy here because the next load has a higher resistance and I need to give it ¾ of my energy”. How do they pull off these amazing feats of collaboration and foresight? For years I was genuinely stumped when trying to explain the rationale behind series and parallel phenomena; my attempts were all variations of “well, because that’s what happens”.

How do electrons “know” that there is another resistor connected in series down the road? How do they “know” which parallel path to choose? For that matter, how does a battery connected to a single resistor “know” how much current to push? There are so many mysteries of simple electric circuits! Let's explore the last question first, which will help us answer all the others. Read More...

The Hole Truth: Why black holes aren’t what you’ve probably been told they are!

Philip Freeman, teacher at Richmond Secondary School (Richmond BC), Executive member BCAPT

Black holes are big news these days. Unfortunately a significant number of statements in the press are not only mistaken but wrong in ways that obscure the truly interesting and important things we know about black holes. This article hopes to clarify a number of points about what black holes are and are not. Read More...

Hands-On Fields

Roberta Tevlin
Teacher at Danforth CTI, Manager OAPT Newsletter

The concept of fields is fundamental to our modern understanding of physics and the Ontario curriculum dedicates one of the five units in 12U physics to Gravitational, Electric and Magnetic Fields. I have struggled for many years to find ways to make this important but abstract concept more tangible to my students. Here is what I have come up with so far. Read More...

An Inexpensive Magnetometer

Dave Doucette (OAPT President) Richmond Hill High School, Richmond Hill, Ontario

Several years ago I was in need of a cheap, easily assembled, sensitive magnetometer. The intent was to design a tool for students to palpably observe the magnetic field around a current carrying conductor. Deflection of a compass needle lacked the ‘wow factor’ I sought. The solution turned out to be beautiful in its simplicity. Read More...
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