2006-11-17 20:38:39 · 5 answers · asked by arka_spacerocker 2 in Science & Mathematics ➔ Physics
How's your trip?
2006-11-17 20:40:11 · answer #1 · answered by just browsin 6 · 0⤊ 0⤋
I'm not quite sure how well I'm going to explain this, but I'll try.
It's due to the speed of the rotating blades, and won't happen with all fans, it depends largely on the speed of the specific fan.
Your brain, as quickly as it can register new information, can only do so at a limited rate. I believe it's somewhere in the region of 50 images per second (which could be considered equivalent to 50Hz).
The speed of the fan you're viewing is such that every 50th of a second, one of the blades is just about to reach the position that was occupied by another blade in the previous image registered by your brain. As a result, they appear to be rotating backwards.
Notice that when you switch the fan off, as the blades slow down, they will alternately appear to be moving forwards and backwards, until eventually they're at a speed where you can actually keep up with them.
2006-11-17 22:40:53 · answer #2 · answered by Ramrider 2 · 0⤊ 1⤋
I love made up answers.
The light in the room is actually flickering 60 times a second. Your eye can't usually pick that up, but it creates a strobe light effect on the fan blades. The blades change brightness a little every 60th of a second, so if the blades are going by in a little less time than that, they'll be brighter a little sooner each time and appear to go backwards.
2006-11-18 10:39:52 · answer #3 · answered by Nomadd 7 · 1⤊ 0⤋
It is an illusion. The fan is always going the one direction, but because they are going so fast, your eyes make it look like they are going the opposite way. Same happens with tyres. if ur in the passanger seat and you watch the tyres of a car next to you.. :-)
2006-11-17 20:43:10 · answer #4 · answered by Anonymous · 0⤊ 1⤋
Some of these answers are hilarious
2015-01-19 23:51:41 · answer #5 · answered by Stevo 1 · 0⤊ 0⤋