Biology; Chemistry; Physics: Post your doubts here!

[Anon]

I follow you abcde..

You mention current will flow where resistance is zero.

If both path have resistance, it will flow through both, current being larger in the one with lesser resistance..

But here at the junction,
if current just goes through one resisitor, there is 3 ohms resistance
If it goes through both the pathways, there is 3.3333 ohms resistance...

So why does it not take two pathways?
Resistance is not negligible in any of the pathway.

 

[abcde]

u guys i still have confusion.
I 100% agree that when the switch is open so the current will be 1A
=> I = V/R = 6/6 = 1A
but what will be the working of second?
I mean won't the current be shared as now we are making it a parallel circuit.
when current will pass through 1st resistor the current will be 2A
=> I=V/R =6/3 =2A
but when it comes to the second it gets shared into 1:1 ratio as its a parallel circuit.?

The closing of the switch does not make it a parallel circuit. The two resistors are still connected in series. It would've been a parallel circuit if the first resistor was mounted on the wire containing the switch.

I follow you abcde..

You mention current will flow where resistance is zero.

If both path have resistance, it will flow through both, current being larger in the one with lesser resistance..

But here at the junction,
if current just goes through one resisitor, there is 3 ohms resistance
If it goes through both the pathways, there is 3.3333 ohms resistance...

So why does it not take two pathways?
Resistance is not negligible in any of the pathway.

It does not take two pathways because after flowing through the first 3 ohm resistor, it can either flow through the other 3 ohm resistor or it can choose a path with (almost) 0 resistance. It does the later as I explained previously.

 

[Anon]

Woo hoo..

I think I finally understood the main thing... I got how it is zero resistance.

but one thing still:

The closing of the switch does not make it a parallel circuit. The two resistors are still connected in series. It would've been a parallel circuit if the first resistor was mounted on the wire containing the switch..

Why is it not paralell?
Can you explain explicitly the bolded part?

 

[SalmanPakRocks]

Woo hoo..

I think I finally understood the main thing... I got how it is zero resistance.

but one thing still:

The closing of the switch does not make it a parallel circuit. The two resistors are still connected in series. It would've been a parallel circuit if the first resistor was mounted on the wire containing the switch..

Why is it not paralell?
Can you explain explicitly the bolded part?

Can u make me understand it too??

 

[Anon]

Look Salman,

When there is zero resistance in one path, and resistance in other, the current go only through low resistance path,
Follow the wire from positive terminal... After it have passed the resistor, there there is zero resistance if it go through the middle wire, whilr there would be resistance if it continues ahead.. So therefore it doesnt pass through second resistor....

I think, abcde example of short circuiting was just too awesome... It is a perfect example when current take zero resistance path, and not take pathways...

 

[abcde]

The second diagram here corresponds to the bolded part.
The first diagram is not a parallel circuit as the resistors are connected in series.
Really hope you understand.

 

[SalmanPakRocks]

Look Salman,

When there is zero resistance in one path, and resistance in other, the current go only through low resistance path,
Follow the wire from positive terminal... After it have passed the resistor, there there is zero resistance if it go through the middle wire, whilr there would be resistance if it continues ahead.. So therefore it doesnt pass through second resistor....

I think, abcde example of short circuiting was just too awesome... It is a perfect example when current take zero resistance path, and not take pathways...

So this means Current will travel through the path which has least resistance and if we take the example of question above, then the current won't flow through the second resistor right?

 

[Anon]

Thanks for taking the pain of Ms Paint (unintentional allitration)

I got it, finally.
This question was bugging me from God know how long...

Thanks a lot again..

 

[SalmanPakRocks]

The second diagram here corresponds to the bolded part.
The first diagram is not a parallel circuit as the resistors are connected in series.
Really hope you understand.

So this means that a circuit to be a paralled it must have a component attached with its external wire?

 

[Anon]

So this means Current will travel through the path which has least resistance and if we take the example of question above, then the current won't flow through the second resistor right?

Not least.... zero

It takes single path when there is ZERO (negligible) resistance in one of the path.

If two paths have resistance, one having lower, and other higher, current will flow through both, and magnitude of current will be more in the path which have low resistance...


If we were to accept that current flow through least resistance only, this mean current would never go through multiple path, which means no paralell circuit, so it is wrong..

This is what I have understood..

 

[Anon]

So this means that a circuit to be a paralled it must have a component attached with its external wire?

I think it means, that circuit is paralell, when the second component is attach such that the wire connected to the main circuit, encloses the component in that circuit....

 

[Nibz]

Why are you guys stuck in this simple concept?

 

[Anon]

Cause we just started electricity in our schools!! (or atleast me)

+

Exams are nearing, and it is then we realise of our faulty concepts, (when we get stuck in pastpapers)

+

I couldnt PM you

+

*enter a superly complicated reason here*

 

[Nibz]

Don't complicate things.
Direct current always tends to follow the path of least resistance. Fact.
Series circuit: 2 or more resistors connected sequentially such that if there is a break in one, the whole damn circuit shuts down.
Parallel one: 2 or more resistors connected ACROSS each other to one common point of Voltage. Here if one path is broken, current simply flows through the other path.

 

[Anon]

Nibz, did you see the question??

Your definition of series said that

2 or more resistors connected sequentially such that if there is a break in one, the whole damn circuit shuts down.

but in the circuit in the question, if you break the resistor on the right, it doesnt "shut down the whole damn circuit"

 

[Nibz]

It's because there is a WHOLE BIG WIRE WITH A SWITCH there. Even a Kindergarten student knows such things.

 

[Nibz]

Resistance is hindrance to the flow of current, correct? Why would current go through that resistor when there is a motorway like path present!

 

[Anon]

I have understood about the current flow and all, but one question


when switch is closed,

and we break the resistor on the right.

If it doesnt "shut down the whole damn circuit" this means, it isnt series....
While it is !

Explanation required...

 

[Anon]

Bringing diagram to this page for ease:

 

[Nibz]

Oye buddhu, when you provide a separate (easier) pathway for current, the second 3 ohms resistor doesn't share the circuit anymore.
(Even if it does, that's not part of your syllabus)