Resistance of Light Bulbs in Parallel

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SUMMARY

The discussion focuses on calculating the resistance of light bulbs connected in parallel to a 110-V source with a total lead resistance of 1.6 Ω. Each bulb has a current flow of 302 mA, leading to the calculation of individual bulb resistance using the formula Rbulb = V/Ibulb, resulting in approximately 364.24 Ω per bulb. Additionally, participants discuss methods to determine total power and the percentage of power wasted in the leads, emphasizing the importance of understanding voltage drops in parallel circuits.

PREREQUISITES
  • Understanding of Ohm's Law (V=IR)
  • Familiarity with power calculations (P=V^2/R)
  • Knowledge of parallel circuit configurations
  • Basic electrical resistance concepts
NEXT STEPS
  • Calculate total power consumption in parallel circuits
  • Learn about voltage drops across components in parallel
  • Explore the implications of lead resistance in electrical circuits
  • Study advanced circuit analysis techniques for complex configurations
USEFUL FOR

Students in electrical engineering, educators teaching circuit theory, and anyone interested in understanding the principles of electrical resistance in parallel circuits.

Angie K.
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Homework Statement


Eight lights are connected in parallel to a 110-V source by two long leads of total resistance 1.6 Ω.

a. If 302 mA flows through each bulb, what is the resistance of each?

b. What percent of the total power is wasted in the leads?

Homework Equations


V=I
P=V^2/R

R. The attempt at a solution

I found the total resistance to be 45.5298 V but when plugging that into find the resistance of each bulb, I can't seem to get to the right answer. What am I missing here?
 
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Angie K. said:

Homework Statement


Eight lights are connected in parallel to a 110-V source by two long leads of total resistance 1.6 Ω.

a. If 302 mA flows through each bulb, what is the resistance of each?

b. What percent of the total power is wasted in the leads?

Homework Equations


V=I
P=V^2/R

R. The attempt at a solution

I found the total resistance to be 45.5298 V but when plugging that into find the resistance of each bulb, I can't seem to get to the right answer. What am I missing here?

It can be calculated in many ways (how did you do it?).

1) You can find the resistance in one bulb, (Rbulb=V/Ibulb), after that finding Rtotal in 8 bulbs in parallel.
2) You can find the total power, after that using Ptotal=V2/Rtotal
3) You can find the total current, after that using Rtotal=V/Itotal
 
Last edited:
Hesch said:
It can be calculated in many ways (how did you do it?).

1) You can find the resistance in one bulb, (Rbulb=V/Ibulb), after that finding Rtotal in 8 bulbs in parallel.

That is what I used
Rbulb=V/Ibulb
=110V/.302
=364.238 shouldn't that be the resistance of each bulb? Or do I have to find the voltage drop for eacg lightbulb?and divide it by the total current (wouldn't that just give me the resistance for all the bulbs?)
 
The voltage drop for each bulb is 110V (bulbs are in parallel). Your Rbulb is correct, and so is your Rtotal in #1.

But then I cannot understand this in #1:

Angie K. said:
but when plugging that into find the resistance of each bulb, I can't seem to get to the right answer. What am I missing here?

What's your problem here?
 
Last edited:

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