I had left out my oscilloscope attached to an Air Core Solenoid that I use
to demonstrate EM induction by pushing a magnet in and out of the coil. I
had done this in a different location in the room than normal and
uncovered, therefore, a new event for me. This morning some students were
repeating the demo, playing, and I noticed that instead of a dot being
deflected it was a vertical line. Why the line? The answer came quickly as
the coil was moved away from a computer that was operating today, but not
yesterday. A horizontal sweep gave us a frequency of 50kHz. Then I changed
the screen resolution and the amplitude of the induction dropped and
depending on which resolution I used I found a different wave form with
different frequencies. I do not know much about computer monitors but am
hoping to learn.
Any ideas?
Ken Fox
AP/IB Physics Teacher
Smoky Hill High School
Aurora, CO