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

[prishila]

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?

 

[CWatters]

Parallel: U=U1=U2=U3

So what happens (for example) to U2 and I2 if Bulb 1 or 3 fails?

 

[prishila]

U2 doesn't change and I2 ... I don't know, it becomes greater?

 

[cnh1995]

Consider three bulbs in parallel and U1=U2=U3. If bulb 1 fails, how will it affect U2 and U3?

 

[prishila]

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.

 

[cnh1995]

U2 will continue being equal to U3 and won't change.

Right. Hence, the remaining bulbs continue to light.

 

[Algr]

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.

 

[CWatters]

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?