ATAR Notes: Forum

VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: Try_Beast on November 13, 2012, 03:13:28 pm

Title: Parallel Circuits...
Post by: Try_Beast on November 13, 2012, 03:13:28 pm: Just to confirm, if there are three parallel wires, all of which are connected to a battery source, that have a certain number of globes in each of them...and one of the globes in one of the wires breaks/stops functioning..then only the globes in that wire will stop working right?

But what about the brightness of the other globes in the other two wires..will they have the same brightness or be brighter than before?? Please explain thoroughly, thankss.
Title: Re: Parallel Circuits...
Post by: StumbleBum on November 13, 2012, 03:28:48 pm: Quote from: Try_Beast on November 13, 2012, 03:13:28 pm
Just to confirm, if there are three parallel wires, all of which are connected to a battery source, that have a certain number of globes in each of them...and one of the globes in one of the wires breaks/stops functioning..then only the globes in that wire will stop working right?

Yes, only the globes that are in the wire with the blown globe will stop working.

Quote from: Try_Beast on November 13, 2012, 03:13:28 pm
But what about the brightness of the other globes in the other two wires..will they have the same brightness or be brighter than before?? Please explain thoroughly, thankss.

~~The globes would now glow brighter because they will receive more current than before according to the formulae:~~

~~$I_{T} = I_{1} + I_{2} + I_{3}$~~

~~So if you remove one of the branches of the parallel circuit the $I_{1}$ and $I_{2}$ will now have to be larger to account for the $I_{T}$ that has to stay the same.~~

EDIT: That's wrong, my memory of electricity is shoddy to say the least.
Title: Re: Parallel Circuits...
Post by: haider543 on November 13, 2012, 03:47:58 pm: are you sure? because every question ive done like this,in the answer the brightness of the other rows stays the same once one row is not working anymore, because the voltage will still be the same in the working rows after the one row is blown, hence current is the same?
Title: Re: Parallel Circuits...
Post by: nerfsdacier on November 13, 2012, 04:06:25 pm: Voltage stays same, I always thought total current would decrease as you are increasing effective resistance. However I think that the haider is right, the brightness should stay the same...

P = VI = V^2/R, both V and R stay same, so brightness stay the same.
I could be wrong, it's been a while haha
Title: Re: Parallel Circuits...
Post by: availn on November 13, 2012, 04:34:25 pm: Batteries don't always give a constant current. If you remove a light bulb, then the combined current drawn by the remaining bulbs will be less.

A bulb will have a power rating, P. In parallel, the voltage going through a bulb is always the same, and P = V^2/R, so the resistance of the bulb will remain constant for that voltage. If you remove a bulb, you are adding total resistance to the circuit, as the loads are wired in parallel, so you will draw less current for each bulb removed.