Light Bulbs in Series vs. Parallel

In summary, the two 120V light bulbs, one 25W and one 100W, were connected in parallel with 120V across each. When they were connected in series across a 240V power line, one of them burned out immediately. To determine which one burned out, the resistances of each bulb in the 120V circuit were calculated and then the total system current was found when they were in series with the 240V source. By comparing the calculated power of each bulb with its rating, it was determined which one would burn out.
  • #1
kimberlyann9
13
0

Homework Statement


You have two 120V light bulbs, one 25W and one 100W, that are normally connected in parallel with 120V across each. Your friend had what seemed like a good idea which was to connect them in series across a 240V power line. However, one of them burned out immediately. Which one burned out and why?


Homework Equations


P=IV
P=I^2*R


The Attempt at a Solution


If light bulbs are in series, the same current flows through both of them. Should I treat this like a resistor problem and calculate the resistor of the light bulbs in both cases? I'm not sure how to figure out which one burns out.
 
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  • #2
kimberlyann9 said:

Homework Statement


You have two 120V light bulbs, one 25W and one 100W, that are normally connected in parallel with 120V across each. Your friend had what seemed like a good idea which was to connect them in series across a 240V power line. However, one of them burned out immediately. Which one burned out and why?


Homework Equations


P=IV
P=I^2*R


The Attempt at a Solution


If light bulbs are in series, the same current flows through both of them. Should I treat this like a resistor problem and calculate the resistor of the light bulbs in both cases?
Yes.
I'm not sure how to figure out which one burns out.
As you stated, first calculate the resistance for each bulb in the 120 volt circuit. The resistances of your light bulbs are fixed values. Then putting them in series with 240 volt source, you will find the total system current. From that you can determine the power consumed by each bulb. Comparing the calculated power of each bulb with it's rating will make it obvious which one would burn out.
 
  • #3
OmCheeto said:
Yes.

As you stated, first calculate the resistance for each bulb in the 120 volt circuit. The resistances of your light bulbs are fixed values. Then putting them in series with 240 volt source, you will find the total system current. From that you can determine the power consumed by each bulb. Comparing the calculated power of each bulb with it's rating will make it obvious which one would burn out.

Okay great, thanks for your help!
 

What is the difference between light bulbs in series and parallel?

In a series circuit, the light bulbs are connected in a single loop, where the current flows through each bulb in succession. In a parallel circuit, the light bulbs are connected to the same power source but each bulb has its own individual loop for the current to flow through.

Which arrangement is more efficient for light bulbs, series or parallel?

Generally, a parallel circuit is more efficient for light bulbs. In a series circuit, if one bulb burns out, the entire circuit will be broken and all the bulbs will turn off. In a parallel circuit, if one bulb burns out, the other bulbs will still stay lit. This means that the overall brightness of the light bulbs will be maintained in a parallel circuit, while it will decrease in a series circuit if bulbs burn out.

How do light bulbs in series and parallel impact the overall brightness of the light?

In a series circuit, the overall brightness of the light bulbs will decrease as more bulbs are added because the voltage is divided between each bulb. In a parallel circuit, the overall brightness will stay the same regardless of the number of bulbs because each bulb has its own voltage source.

Can you mix light bulbs in series and parallel in the same circuit?

Yes, it is possible to have a combination of light bulbs in series and parallel in the same circuit. This is often seen in household lighting where multiple light fixtures may contain both series and parallel connections.

How can I calculate the total resistance in a series or parallel circuit?

In a series circuit, the total resistance is equal to the sum of all the individual resistances of the bulbs. In a parallel circuit, the total resistance is calculated using the formula 1/Rt = 1/R1 + 1/R2 + 1/R3... where Rt is the total resistance and R1, R2, R3... are the individual resistances of the bulbs.

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