Current through the circuit with resistor and light bulb

AI Thread Summary
The discussion revolves around calculating the current in a series circuit containing a resistor and a light bulb. The user initially assumes the bulb has zero resistance, leading to confusion when the expected answer is 0.3Ω instead of 0.45Ω. It is clarified that the resistance of the bulb is variable and not zero, as indicated by a graph. A suggested approach is to use an iterative graphical method to estimate the lamp resistance by starting with an assumed value and refining it based on the resulting current. This method aims to converge on the correct lamp resistance for accurate current calculation.
ashyau
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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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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?
 
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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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