I have a fan. When you turn it on it spins very fast. If i slow it down then i see the fan turn right then left then slows down. Another example is if you see a fast moving car go to the right >>>
At a certain speed the wheel will turn left then rotate to the right faster. In other words when something starts rotating at a fast speed at a certain point it will look as if the object rotating rotates to the left then to the right. Sorry if it does not mAke sense.
At a certain speed the wheel will turn left then rotate to the right faster. In other words when something starts rotating at a fast speed at a certain point it will look as if the object rotating rotates to the left then to the right. Sorry if it does not mAke sense.
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This is the stroboscopic effect and it occurs if the object is viewed under a flickering light.
This includes tv and of course all of our interior lights flicker either 100 per sec (50 Hz) or 120 per sec (60 Hz).
What happens is that the light turns on briefly and you get a picture of the fan at this point.
Now the light diminishes and the fan moves forwards by some amount.
Once more the light turns on. The apparent position of the fan blade can now vary depending on how far the fan has turned during the interval.
If the fan has turned slightly LESS than the spacing of the blades ( actually it is N * blade spacing - delta) then it will appear to you as though it has turned backwards a small amount.
As the fan gets slower then it turns even less again in this interval and the fan will not only appear to be going backwards but it will seem to be gaining speed.
If it slows down enough then instead of the brain perceiving it to be half an interval before the previous image it will be seen as half an interval ahead.
Now the fan will appear to be moving fast in the opposite direction.
As it gets still slower it seems to be slowing down.
Look up stroboscope for more information and diagrams.
This includes tv and of course all of our interior lights flicker either 100 per sec (50 Hz) or 120 per sec (60 Hz).
What happens is that the light turns on briefly and you get a picture of the fan at this point.
Now the light diminishes and the fan moves forwards by some amount.
Once more the light turns on. The apparent position of the fan blade can now vary depending on how far the fan has turned during the interval.
If the fan has turned slightly LESS than the spacing of the blades ( actually it is N * blade spacing - delta) then it will appear to you as though it has turned backwards a small amount.
As the fan gets slower then it turns even less again in this interval and the fan will not only appear to be going backwards but it will seem to be gaining speed.
If it slows down enough then instead of the brain perceiving it to be half an interval before the previous image it will be seen as half an interval ahead.
Now the fan will appear to be moving fast in the opposite direction.
As it gets still slower it seems to be slowing down.
Look up stroboscope for more information and diagrams.
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its the lighting