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Homework Help: How to determine the brightness of a light bulb

  1. Feb 25, 2007 #1

    cy19861126

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    In general, does more current/less resistence mean the brighter of the light bulb? How does voltage take into account in this case
     
    cy19861126, Feb 25, 2007
  2. jcsd
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  3. Feb 25, 2007 #2

    ranger

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    Both the current and voltage contributes to the brightness. It just depends on the configuration. If an incandescent is 100% efficient (with it isnt btw), that means all power (V*I) would be used to produce visible light rather than 90% being wasted as heat.
     
    ranger, Feb 25, 2007
  4. Feb 25, 2007 #3

    turdferguson

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    "Brightness" is a measure of power, so at constant voltage power is I^2R. If resistance is decreased and current is increased by an equal factor, the increase in current counts for more and the bulb will appear brighter
     
    turdferguson, Feb 25, 2007
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