Resistance of a light bulb question

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Homework Help Overview

The discussion revolves around calculating the resistance of light bulbs based on their power ratings and voltage specifications, specifically focusing on a 75.0 W bulb connected to a 190 V power source and a 120 W bulb. The subject area includes electrical circuits and power calculations in alternating current (AC) systems.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply formulas related to power and resistance but questions the correctness of their approach. Some participants suggest using the relationship R = V²/P for AC circuits and discuss the implications of average versus maximum voltage. Others inquire about the necessity of converting frequency to angular frequency and how to account for the power source connection.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and clarifying concepts related to AC circuits. Guidance has been offered regarding the use of specific formulas, but there is no explicit consensus on the approach to take.

Contextual Notes

Participants have noted the need to understand the relationship between peak and RMS values in the context of AC circuits, indicating that some foundational concepts may still need to be addressed.

Pepsi24chevy
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Hey guys I am having some trouble with this simple questions:
What is the resistance of a light bulb that uses an average power of 75.0 W when connected to a 60.0 Hz power source having a maximum voltage of 190 V?


(b) What is the resistance of a 120 W bulb?

I tried doing it by (75/190)^2 * (2pi60) but this is not correct.
 
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One has to apply the equivalent of P = V I = V2/R = I2R for AC, so R = V2/P.

Since it is pure resistance, i.e. no reactance, the voltage and current are in phase.

Think of average and maximum.
 
Ok, do i still have to multiply the 60hz by 2pi? Also, how do i handle it being connected to the power source?
 
no but thanks for the link. I think that should of helped me get an idea
 

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