Successive powers of the imaginary unit j correspond to a rotation. Created by Willy McAllister.
The concept of negative frequency is perplexing, but it makes sense when you think about rotating complex exponentials.
Sine and cosine can be generated by projecting the tip of a vector onto the y-axis and x-axis as the vector rotates about the origin. Created by Willy McAllister.
If we introduce time as the argument to the sine function, we get a sine wave. Animated. Created by Willy McAllister.
A quick review of some ideas from trigonometry that will help us with AC analysis. The definitions of sine, cosine, and tangent, circles, degrees, radians. Created by Willy McAllister.
Engineering vocabulary revision
Students use conductivity meters to measure various salt and water solutions, as indicated by the number of LEDs (light emitting diodes) that illuminate on the meter. Students create calibration curves using known amounts of table salt dissolved in water and their corresponding conductivity readings. Using their calibration curves, students estimate the total equivalent amount of salt contained in Gatorade (or other sports drinks and/or unknown salt solutions). This activity reinforces electrical engineering concepts, such as the relationship between electrical potential, current and resistance, as well as the typical circuitry components that represent these phenomena. The concept of conductors is extended to ions that are dissolved in solution to illustrate why electrolytic solutions support the passage of currents.