Hello guys:-),

 

I have one more question. I'm not really sure that the answer to this question is current pathway anyway

 

 

 

 

all the resitors are 100 ohms. Why is that when the witch is closed the voltage of resistor 1 is 15. Is it because when the switch is closed the current takes the path with least resistance. I checked about this least resistance thing in the internet and they say that it is not always the case. Any help would be appreciated. Thanks:-)

Didn't you say all of them are 100 ohms?

Nothing will change the resistance of an individual resistor. When the switch is in the "open" position (like in your picture) the resistance of the entire circuit is 150 ohms, which is what I think you mean.

If the switch is "closed" (the top wire connected), you will have a total resistance of 100 ohms.

You need to look in a book, on wiki, or a website on how resistors combine is series and in parallel.

In general, the current through resistors in parallel is inversely proportional to resistance, so yes, most of the current takes the path of the least resistance.

However current is the same through a number of series resistors, regardless of each individual resistance.

you may count R2 and R3 as a single 50 Ohm resistor, making Rtot 150 Ohm with the switch open, when you Close the switch you bypass the 50 Ohms leaving only the 100 Ohm to sink any current.

 

across Rtot (switch Open) you will have your 15v, across R1 you will have 10v and across the switch you`ll have 5V, when you Close the switch the entire 15v is across R1.

However, it is not true that current takes the path of least resistance — that's an oversimplification. If resistors 2 and 3 were unequal (say, R2<R3), the current (with the switch open) would not all flow through #2. The current flow would be proportional to 1/R, so that the voltage drop were equal across each.

 

Even in the example, if real wires are present, there will be a tiny current in 2 and 3 with the switch closed.

However, it is not true that current takes the path of least resistance — that's an oversimplification. If resistors 2 and 3 were unequal (say, R2<R3), the current (with the switch open) would not all flow through #2. The current flow would be proportional to 1/R, so that the voltage drop were equal across each.

 

Even in the example, if real wires are present, there will be a tiny current in 2 and 3 with the switch closed.

 

Thanks everyone who helped. Really appreciate it:-). I know how to work out the voltage when the switch is closed I just wanted to do know if it bipases in the second instance.I have another small question in a parallel circuit does some current flow to every circuit or does it take the path with least resistance.

Thanks everyone who helped. Really appreciate it:-). I know how to work out the voltage when the switch is closed I just wanted to do know if it bipases in the second instance.I have another small question in a parallel circuit does some current flow to every circuit or does it take the path with least resistance.

 

I believe you get a fraction of the current depending on the resistance of the path, so the least resistive path gets the highest current.

OMG, that pic is 'paint made'!

Think of it as water moving down pipes.

 

In a series circuit all the water goes through all the pipes, it can't just dissapear. In parallel if there's a water pressure (equivalent to voltage) then most of the water will go down the path of least resistance, but a little bit of water will still go down the other paths, unless there's a complete blockage (i.e. infinite resistance).