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Thread: Broca-Sulzer phenomenon

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    OptiBoard Professional yzf-r1's Avatar
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    Broca-Sulzer phenomenon

    I wonder if there is anyone out there that can help me solve this 'puzzle'

    Since the broca-sulzer phenomenon is where lights flashed at 50-100 Hz appear brighter than they actually are, is it true that a rotating disc (e.g a fan) if placed infront of a light bulb, such that the light appears to flash at 50-100 Hz, would this bulb appear brighter than it actually is?

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    Objection! OptiBoard Gold Supporter shanbaum's Avatar
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    Re: Broca-Sulzer phenomenon

    yzf-r1 said:
    I wonder if there is anyone out there that can help me solve this 'puzzle'

    Since the broca-sulzer phenomenon is where lights flashed at 50-100 Hz appear brighter than they actually are, is it true that a rotating disc (e.g a fan) if placed infront of a light bulb, such that the light appears to flash at 50-100 Hz, would this bulb appear brighter than it actually is?
    I don't know the answer to your question, but I think you meant 50-100 milliseconds (10-20 Hz). The maximum effect (adding in the "off" time) is found at 8-10 Hz.

    If I have to guess, I'd say, no, because a fan would not sufficiently block the light from the source (unlike turning it off). I understand the effect to be a physiological one based on the way we perceive the transition from darkness to light - that, to put it simply, a light seems brighter during the first 50-100 milliseconds after it's switched on.
    Last edited by shanbaum; 08-10-2002 at 01:59 PM.

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    OptiBoard Professional yzf-r1's Avatar
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    Re: Re: Broca-Sulzer phenomenon

    Shanbaum,

    shanbaum said:
    I don't know the answer to your question, but I think you meant 50-100 milliseconds (10-20 Hz). The maximum effect (adding in the "off" time) is found at 8-10 Hz.
    You're right when you say that i probably meant 50-100ms, because i did.

    I thought it would be a really cheeky way of increasing the apparent brightness for lower wattages, but it is rather useless since the human eye will be able to detect the flicker at 10 Hz

    interesting nevertheless!!!
    :)

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