Resistance of Light Bulbs in Parallel

In summary, eight lights are connected in parallel to a 110-V source using two long leads with a total resistance of 1.6 Ω. By using the equations V=I and P=V^2/R, the attempts to find the resistance of each bulb using the total resistance value of 45.5298 V were not successful. However, the correct resistance for each bulb can be found using the equation R=V/I, with a resistance value of 364.238 Ω. The total power can also be calculated using P=V^2/R.
  • #1
Angie K.
108
1

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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  • #2
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:
  • #3
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?)
 
  • #4
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:

Related to Resistance of Light Bulbs in Parallel

1. What is the purpose of connecting light bulbs in parallel?

Connecting light bulbs in parallel allows them to operate independently of each other, meaning if one bulb burns out, the others will still continue to function. It also ensures that each bulb receives the same voltage, resulting in a consistent brightness.

2. How does the resistance of light bulbs in parallel compare to that of light bulbs in series?

When light bulbs are connected in parallel, the total resistance decreases as compared to connecting them in series. This is because the current is divided among the parallel bulbs, reducing the overall resistance in the circuit.

3. What is the formula for calculating the total resistance of light bulbs in parallel?

The formula for calculating the total resistance in a parallel circuit is 1/Rt = 1/R1 + 1/R2 + 1/R3 + ..., where Rt is the total resistance and R1, R2, R3, etc. are the individual resistances of each bulb.

4. Can the resistance of light bulbs in parallel be different from each other?

Yes, the resistance of light bulbs in parallel can be different from each other. However, it is important to note that the more similar the resistances are, the more evenly the current will be divided among the bulbs.

5. How does the brightness of each light bulb in a parallel circuit compare to the others?

In a parallel circuit, each light bulb will have the same brightness as the others, as they all receive the same voltage. This is in contrast to a series circuit, where the bulbs at the end of the circuit may be dimmer due to a decrease in voltage.

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