Multiple-Concept Example 9 reviews the concepts that are important to this probl
ID: 1423821 • Letter: M
Question
Multiple-Concept Example 9 reviews the concepts that are important to this problem. A light bulb is wired in series with a 132-? resistor, and they are connected across a 120.0-V source. The power delivered to the light bulb is 22.8 W. What is the resistance of the light bulb? There are two possible answers. Give the larger of the two.
Chapter 20, Problem 046 Multiple-Concep xample 9 reviews the concepts that are important to this problem. A light bulb is wired in series with a 132- resistor, and they are connected across a 120.0-V source. The power delivered to the light bulb is 22.8 W. What is the resistance of the light bulb? There are two possible answers. Give the larger of the two. Light bulbR2 Number Units the tolerance is +/-296Explanation / Answer
Let the resistance of bulb be R ohm
Rnet = R1+ R2
= ( R + 132 ) ohm
V across bulb = R1 *V/ (R1+R2)
= R*120 / (R+132)
P of bulb = V^2/R
22.8 =( R*120 / (R+132))^2 / R
22.8 =R*120^2 / (R+132)^2)
22.8*((R+132)^2) = 14400*R
22.8*(R^2 + 132^2 + 264*R) = 14400*R
22.8*R^2 + 397267.2 + 6019.2*R = 14400*R
22.8*R^2 -8380.8*R + 397267.2 = 0
Solving for R,
R= 311.7 ohm and R = 55.9 ohm
Answer: 311.7 ohm
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