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Current through the circuit with resistor and light bulb

  • Thread starter ashyau
  • Start date
  • #1
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Homework Statement



Problem is give in the image


Homework Equations



V=IR

The Attempt at a Solution



Since its a series circuit i tried that current should be the same so it's 9/20 since there is no resistance in the bulb which is 0.45 Ω somehow the answer is 0.3Ω. why is that the case? should be something to do with the graph but i have no idea what to do with it
 

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Answers and Replies

  • #2
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In the image you've provided, it's difficult to tell what's being asked. I assume that you're supposed to finish the sentence: The current in the circuit is ______. Is that correct?
 
Last edited:
  • #3
lewando
Homework Helper
Gold Member
1,349
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The resistance in the lamp is not zero. It is variable--described by the curved dashed line. The answer has units of "A", not "Ω". Try an iterative graphical approach--pick some starting value for the lamp resistance, say 20Ω, find the resulting current then use that current to determine a better value for lamp resistance. Repeat process until your lamp resistance converges.
 

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