Lesson 27: Electric fields and Coulombs law
If students have grasped the idea of gravitational fields then electric fields can be dealt with quite quickly. I always start by showing why scientists started to define electrical quantities with some simple electrostatics experiments. The sweater and balloon simulation from Phet is good here as it not only works every time but enables you to see the different charges. Without going into potential its difficult to explain how most of the classic electrostatics experiments work so it best to keep it simple.
Page 195 - 199
SMART board Notes
This is a great way of starting this part of the syllabus. You can show how the balloons attract to the sweater but repel from each other. if you put one balloon onto the sweater then the other balloon does not experience any force showing how charges cancel. I always ask my students "what has two types that add, subtract and cancel each other out?". The answer is numbers but they never get it.
This applet can be used to map field lines for different arrangements of charge (circles, parallel plates and arrangement of points. The "show field lines" option doesn't show the field lines as we would like them to be draw, more line a series of arrows than continuous lines.
Although difficult to see in the thumbnail this applet by Paul Falstad shows how the fields would look in 3D. You can also show how particles would accelerate if placed in the field. You can rotate the 3D view with your mouse (hand on SMART board) if you give it a flick it starts to rotate on its own. A cool trick on the board.