Found something odd while procrastinating, fan/computer

  • Context: High School 
  • Thread starter Thread starter Rainbrew
  • Start date Start date
Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
Sign up Log in
5 replies · 2K views
Rainbrew
Messages
3
Reaction score
0
So while not doing what I should be I was cooling myself off with this tiny fan with a hand-crank. For some odd reason I decided to point it at my monitor and make it go in reverse and noticed that at a certain speed the blades of the fan appeared to be blue and yellow and rotating in the opposite direction of the actual rotation of the fan. What causes this to occur? I assume it has something to do with the refresh rate of my monitor but I'm clueless as to why this happens. Thanks in advance!
 
Physics news on Phys.org
Chestermiller said:
It must be a stroboscopic effect, like in the movies when the wheels of the stage coach seem to be moving backwards.
What about the colours? I understand that computer light is naturally heavily saturated with blue, however the polarising filter gets rid of most of that light, so where does the blue and yellow come from?
 
It's a psycho-optic illusion. I don't recall its name so I can't find a reference to it. If I remember the demonstration, it includes a cylinder with alternating black and white stripes on its surface, parallel with the cylinder axis. The cylinder is spinning w/ axis vertical. I think there was also a strobe light involved. The illusion was that the black and white stripes were seen as colored stripes.

I also seem to recall a similar effect with a spinning disk with either radial or spiral lines on it to create color. I think there was a strobe involved here also.
 
I think it's called the GBTWYB effect.

Get Back To Work Ya Bum.
 
  • Like
Likes   Reactions: Tom.G