Brightness of Light Bulbs in a Circuit

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Homework Help Overview

The discussion revolves around a circuit containing five light bulbs, where four are connected in parallel and one is connected separately. Participants are exploring the brightness of the bulbs based on their configuration and resistance.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are attempting to understand how the arrangement of bulbs affects their brightness, particularly focusing on voltage drops and power delivery. Questions arise about the implications of identical resistances and the need for specific resistance values.

Discussion Status

There is an ongoing exploration of the relationship between voltage, resistance, and brightness. Some participants suggest that knowing the exact resistance values may not be necessary for determining which bulb is brighter, while others emphasize the importance of power dissipation in the bulbs. Multiple interpretations of the circuit's behavior are being discussed.

Contextual Notes

Participants note the lack of specific values for resistance and voltage, which may limit the ability to calculate exact brightness levels. The discussion is framed within the constraints of a homework problem, focusing on conceptual understanding rather than numerical solutions.

ghostbuster25
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Quick question, if i had a circuit of 5 light bulbs whereby 4 were running parellel in a sequence and one was running seperatly, would one be brighter than the others?
sorry if it is hard to visulise :)
 
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I assume from your question that 4 bulb connected in parallel is in series with 5th bulb to a voltage source.
Now assuming all bulbs are identical, i.e., they have same resistances (say x) you can find the total resistance. And if you find voltage drop across these bulbs, you can find which bulb will be brighter.
 
so shall i just substitute x into where the values of resistance would be. I am not given any values for anything
 
Assume each bulb has resistance R and the whole circuit is driven by a source that produces V volts between its two terminals. Remember that the brightness is directly proportional to the power delivered to the bulb (assuming no or identical power loss).

Using these, you should be able to compare their brightnesses.
 
No need to know the value of resistance, because you have to find which bulb is brighter and not how much right?
By simple common sense we know that the bulb with more voltage across it glows brighter. So you may check across which bulb more voltage drop will occur.
 
n.karthick said:
No need to know the value of resistance, because you have to find which bulb is brighter and not how much right?

Even if you knew the value of the resistance, you will need to know much more to actually calculate a value for luminous flux or intensity. Comparison is the only sensible thing that I can see being done given only these pieces of information.

n.karthick said:
By simple common sense we know that the bulb with more voltage across it glows brighter. So you may check across which bulb more voltage drop will occur.

That is only true if the bulbs are identical. As I said the brightness is directly proportional to the power dissipated by the resistor inside the bulb. That's not a function of only the voltage across it. If you aren't convinced, you can easily try this by using two different light bulbs and a 9V battery.
 
so am i right in believing it to be bulb p? the one on its own but in parallel with the others
 
ghostbuster25 said:
so am i right in believing it to be bulb p? the one on its own but in parallel with the others

Which one are you referring to as bulb p?
 

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