Any idea what is a stroboscopic effect?
Answer:
Ever looked at a cars wheel while it's driving? It's rotating colckwise but looks like it's going counter clockwise? That's what it is.
Certainly. A strobe lamp produces a bright but brief flash of light, repeated at a constant interval. A moving scene illuminated by such a lamp will be a series of separate pictures, and thing may look peculiar due to an effect called aliasing. Anytime you are watching a Western movie, and see the stagecoach wheels apparently turning backward, that is what is happening.
In its simplest form, a rotating disc with evenly-spaced holes is placed in the line of sight between the observer and the moving object. The rotational speed of the disc is adjusted so that it becomes synchronised with the movement of the observed system, which seems to slow and stop. The illusion is caused by temporal aliasing, commonly known as the 'stroboscopic effect'.
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As this is the engineering section, a common use of the effect is the strobe timing light, that flashes everytime No 1 cylinder sparks. The effect freezes the crankshaft pulley with it's attendant timing marks.
A very handy instrument indeed.
forget all the rubbish about discos and such,,,the strobe light was invented to tune car engines,,,different cars vary but assume that the correct position for a spark plug to "fire" is 5 degrees before top dead centre,
on the flywheel pulley which drives the water pump ,alternator etc you will see a knotch,put there by the maker,to show where the engine should fire,,
the strobe is connected between the spark plug and the distributor and flashes when the spark plug fires,it is pointed at the pulley wheel and gives the effect of the pulley wheel standing "still".the distributor can then be turned on its axis until the light shows the knotch in line with the spark plug"flash"making it easy to get the spark plug to "fire" in exactly the right time and place.
it is mostly obsolete nowadays with cars now having electronic ignition and such and basically its a flashing light now used in discos and films.
some people find these flashing lights disturbing and it makes them ill thats why films will state "this film contains flashing lights some people may find disturbing"warnings..
sorry its a bit over simplified or maybe it has confused you even more.
Aha,
Not to do with light strobes, but in a research & developent department, I put myself on a table that vibrated at about 7Hz. the natural frequency of a human body. I I not sure that I have fully recovered, as I then went to Uni, and subjected myself to a trial of stroboscopics in a chamber, and came out confused and dizzy. I am told that such matters are natural.
Hey Ho, if it were not for that that, I probablly would of not written fine songs.
Bob.
A stroboscopic effect occurs when a series of events is viewed through a device which filters out many of the instant view-moments.
So, if there were ten events (a person taking ten strides, say) but a filter prevented you seeing 9 of them, then the legs would be seen to be striding along at a different speed. O.K.?
Now, the "apparent "speed might appear to be faster or slower than the real thing, which is why the car-wheels in movies seem to slow down, go backwards, and phenomona like that, while the car actually travels forward.
But it can also be used positively, for instance to slow down the apparent movement of insects' wings, or humming birds, or seagull's wings, and then you can study exactly what movements they make, to allow them to fly.
I used to use strobes to view vibrating propellor blades, and turbine blades, and observe how they went into resonance and finally snapped. That was at Rolls-Royce.
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