Today was an important day... I taught four classes back-to-back and my associate teacher was away ill. For Physics Grade 11 we covered wave interference and superposition, leading up to the formation of standing waves. After an introduction, some brief examples of superposition when two waves meet, and a step-by-step diagram of node formation through the meeting of a crest and a trough of equal magnitude, I showed a simulation: http://www.walter-fendt.de/ph14e/stwaverefl.htm
This simulation really helped me to understand particle motion vs. wave motion and visualize a wave reflecting back on itself. It was a pleasure to share something with students that had given me insight into a concept..... it seemed to be working for them too... I heard some "Oh!"s ripple through the class.
We ended the class with talking about harmonics and demonstrating standing wave formation on a string attached to a vibrator (weights hanging on the other end to keep it fixed). We increased the frequency of vibration to find the fundamental, first, second and third harmonics. A number of students needed to see a node for themselves to really believe that there were points that remained perfectly stationary throughout the interference.
In Grade 11 Math we introduced periodic behaviour, talked about the periodic nature of trig functions and manually sketched some graphs of sine x and cosine x. I thought it would be too simple and they would get bored really quick, but both classes seemed engaged by the exercise. It's hard to know what students know, what holds their interest... it's often surprising. Tomorrow we move on to transformations of trig functions.
It's neat how we are covering periodic behaviour in both physics and math right now. I see some of the same students in both classes, and they bring up concepts and ideas that we talked about in the other subject... that's a great feeling.
This simulation really helped me to understand particle motion vs. wave motion and visualize a wave reflecting back on itself. It was a pleasure to share something with students that had given me insight into a concept..... it seemed to be working for them too... I heard some "Oh!"s ripple through the class.
We ended the class with talking about harmonics and demonstrating standing wave formation on a string attached to a vibrator (weights hanging on the other end to keep it fixed). We increased the frequency of vibration to find the fundamental, first, second and third harmonics. A number of students needed to see a node for themselves to really believe that there were points that remained perfectly stationary throughout the interference.
In Grade 11 Math we introduced periodic behaviour, talked about the periodic nature of trig functions and manually sketched some graphs of sine x and cosine x. I thought it would be too simple and they would get bored really quick, but both classes seemed engaged by the exercise. It's hard to know what students know, what holds their interest... it's often surprising. Tomorrow we move on to transformations of trig functions.
It's neat how we are covering periodic behaviour in both physics and math right now. I see some of the same students in both classes, and they bring up concepts and ideas that we talked about in the other subject... that's a great feeling.
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