Answers and Tips

  1. The voltage drop across the relay should be around 24V. If it is much higher or lower, you can adjust the voltage with a screw driver to be around 24V.
  2. The current varies a lot here. Typically, I see around 50 mA. When the students measure the current in and out, it will be different. They will get better results if they do not have a negative number.
  3. LaTeX: R\:=\frac{\:V}{I}=\frac{\:24}{.050}=\:480\:Ω
    1. This varies again based on current measurement.
  4. The relay coil should be off and the wires should be removed before taking a measurement. The value should be around 465 to 512, depending upon the coil.
  5. They need to explain whether or not Ohm's Law worked here or not. I want some detail as to why or why not, not just a yes.
  6. They should be using a brown wire for the 24V and a blue wire for the 0V or common.
  7. The rest of the questions are reminders for safety.

Creative Commons License

Unless specified otherwise, any and all work on this page is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.