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How to determine the brightness of a light bulb

  1. Feb 25, 2007 #1
    In general, does more current/less resistence mean the brighter of the light bulb? How does voltage take into account in this case
  2. jcsd
  3. Feb 25, 2007 #2


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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.
  4. Feb 25, 2007 #3
    "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
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