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Mathematics 9 Online
OpenStudy (anonymous):

Can anybody please help me with this?

OpenStudy (anonymous):

OpenStudy (jdoe0001):

well, check your Ohm's law and formula of resistance first :)

OpenStudy (anonymous):

V=I R

OpenStudy (jdoe0001):

is easier to read if it were right side up btw

OpenStudy (anonymous):

resistance in series \[R_{eq}=R_1+R_2+...\] resistance in parallel \[\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2} + ...\]

OpenStudy (anonymous):

How to find Rc? can you explain?

OpenStudy (anonymous):

by applying ohms law you know V and you know I and R = Rc

OpenStudy (anonymous):

V - voltage from battery I- current read from ammeter

OpenStudy (anonymous):

and how do I apply it? can you please explain:(?

OpenStudy (anonymous):

i cannot explain it any further than what i've already said just substitute the values and solve for Rc...

OpenStudy (anonymous):

ohms law is just a simple equation V=I R

OpenStudy (anonymous):

6=1 x R ? is this correct @completeidiot ?

OpenStudy (anonymous):

yes...

OpenStudy (anonymous):

so R is 6 right?

OpenStudy (anonymous):

V = I R, 6 = 1 * R, yes, total R must be 6

OpenStudy (anonymous):

if you have R1=50 OHms and you put R2=1 Ohms in parallel, the total resistance is about 1 Ohms only!(even some less than that)

OpenStudy (anonymous):

And how do I find X?

OpenStudy (anonymous):

so you need that all the resistances combined are =6 what they want you to do is to make a replacement resistor instead of those three and their configuration. the one total resistor (in between battery and monitoring) should be 6

OpenStudy (anonymous):

ok so there's one in series that adds 3 Ohms and you can't do anything about that one. the resistance is already 3 Ohms at least because that has been fixed in the image. The question is, how can we make 3 + two parallel = 6

OpenStudy (anonymous):

ok so far?

OpenStudy (anonymous):

all the branched, layered resistors do have the effect of ONE SIMPLE resistor

OpenStudy (anonymous):

I have no idea :( can you explain?

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

the voltage is considered to be stable no matter how much we draw

OpenStudy (anonymous):

ok so if we have one resistor the voltage of 6V is able to push through it a certain amount

OpenStudy (anonymous):

if we put two resistors in parallel --- we can push the double amount! since there is now two congested pathways, not one.

OpenStudy (anonymous):

this is resistors in parallel, every additional parallel resistor decreases resistance

OpenStudy (anonymous):

because a resistor can be seen from two perspectives; how much does it block, how much does it let through. in parallel, the latter is important.

OpenStudy (anonymous):

Law: resistors in series do add.

OpenStudy (anonymous):

we have 3 Ohm + the parallel branch

OpenStudy (anonymous):

...so the parallel branch must be 3 Ohm, also, to get a total 3+3=6 Ohm

OpenStudy (anonymous):

the 3 Ohm and the parallel branch are in series, right?

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

yes and the total must be 6 Ohms, because of V = R I and 6 = R * 1

OpenStudy (anonymous):

so parallel branch needs to be 3 Ohms

OpenStudy (anonymous):

yes!

OpenStudy (anonymous):

OK, the rule for parallel resistors is actually the following thing: \[R_{total} = \frac{ R _{1}\times R_{2}}{ R_{1}+R_{2} }\]

OpenStudy (anonymous):

we need \[3 = \frac{ 12 \times R_{2}}{ 12+R_{2} }\] , R2 is X

OpenStudy (anonymous):

3=2.4 is what I got

OpenStudy (anonymous):

hmm

OpenStudy (anonymous):

\[3 = \frac{ 12 \times R2}{ 12 } + \frac{ 12 \times R2}{ R2 } \]

OpenStudy (anonymous):

\[3 = \frac{ 12 \times R2}{ 12 } + 12\] i just cancelled the R2 here

OpenStudy (anonymous):

no

OpenStudy (anonymous):

so x would be?

OpenStudy (anonymous):

we have to solve that equation

OpenStudy (anonymous):

the one

OpenStudy (anonymous):

\[3 = \frac{ 12 \times X}{ 12 + X }\] fluttering algebra

OpenStudy (anonymous):

how to solvew for x??

OpenStudy (anonymous):

help

OpenStudy (anonymous):

I am not sure :S

OpenStudy (anonymous):

me neither,ill create a question......

OpenStudy (anonymous):

ok,thanks:)

OpenStudy (anonymous):

\[3 = \frac{ 12 }{ 12 + x } \times \frac{ x }{ 1 }\] \[3 (12+x) = 12 \times \frac{ x }{ 1 }\] \[36+3x = 12 x \] 36 = 9 x x=4

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