Why don't all lights turn off when connected in parallel

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Homework Help Overview

The discussion revolves around the behavior of light bulbs connected in parallel, specifically addressing why some bulbs continue to light when one bulb's filament is broken. Participants explore the implications of parallel connections in electrical circuits.

Discussion Character

  • Conceptual clarification, Assumption checking, Exploratory

Approaches and Questions Raised

  • Participants attempt to understand the relationship between voltage and current in a parallel circuit, questioning how the failure of one bulb affects others. There are inquiries about the role of nodes and the implications of Ohm's law in this context.

Discussion Status

The discussion is active, with participants providing insights into the behavior of voltage and current in parallel circuits. Some have offered analogies to clarify concepts, while others are still grappling with the implications of resistance and current changes.

Contextual Notes

There is mention of specific scenarios, such as Christmas tree lights, which may not follow the same principles due to their design. Participants are also considering the effects of resistance in their discussions.

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Homework Statement


When the filament of a light is broken why do others continue to light?

Homework Equations


Parallel: U=U1=U2=U3
I=I1+I2+I3+...

The Attempt at a Solution


Is it because there are some nodes? How can you explain this simply?
 
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prishila said:
Parallel: U=U1=U2=U3

So what happens (for example) to U2 and I2 if Bulb 1 or 3 fails?
 
U2 doesn't change and I2 ... I don't know, it becomes greater?
 
Consider three bulbs in parallel and U1=U2=U3. If bulb 1 fails, how will it affect U2 and U3?
 
cnh1995 said:
Consider three bulbs in parallel and U1=U2=U3. If bulb 1 fails, how will it affect U2 and U3?
U2 will continue being equal to U3 and won't change.
 
prishila said:
U2 will continue being equal to U3 and won't change.
Right. Hence, the remaining bulbs continue to light.
 
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prishila said:
How can you explain this simply?

The lights are connected in parallel, so power doesn't need to go through one bulb in order to get to the others. It's like ties on a railroad track - you can remove one tie, and the others still touch both sides of the track.

The exception to this is strings of lights for a christmas tree. These are too small to individually accept 120/240 volts, and so are usually connected in series to reduce voltage.
 
prishila said:
U2 doesn't change and I2 ... I don't know, it becomes greater?

The voltage on bulb 2 is the same but the current doesn't increase.

Remember Ohms law says V=IR so

I=V/R

The voltage stays the same, what about the resistance?
 

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