Resistors that doesn't affect the others

[stardust006]

hello! we got this experiment,

R1= 46.8
R2= 46.8
R3= 148.9
R4= 147.7
R5= 217
RT= 71.1

as we can see, r1 and r2 are in series, while r3 and r4 are in series also and they are parallel to each other while r5 is on the middle, we got the RT by solving for r1,r2,r3 and r4.

and here's the question, we did not consider r5 but we got a right RT, what is the r5's work? what does it do on the connection? i am really confused. >.<

 

[256bits]

I do not see a picture but from your expose I assume by R5 being in the middle you mean one end of R5 is connected to where R1 and R2 meet and the other end of R5 is connected to where R4 and R5 meet. If you then calculate the voltage at both ends of R5 you will see that it is the same and thus no current should be flowing through R5. Look up wheatstone bridge.
http://en.wikipedia.org/wiki/Wheatstone_bridge
Note that there is an typo in the wiki article - the first sentence after heading OPERATION should read "..., and resistance of Rx is adjustable."

 

[stardust006]

Yes, thanks a lot! :)