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heeeelppp !!

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halosh92:

--- Quote from: Asamy111 on June 08, 2010, 12:22:27 pm ---oryt

--- End quote ---

both variants?

Asamy111:
varient 1 .. bt still i ddnt gt hw to solve varient 2 too

poisonedrose:
Variant 1:
(a)(i) Well, you know that, in series the Resistors have to be added, right? But there you see from A to C, there’s only one resistor, hence the answer R
(a)(ii)B to X, you see that there are two resistors in parallel, which means that you need to use the formula R*R/R+R (or we can use 1/R+1/R=1/Rt) which is equal to R/2.
(a)(iii) From A to Z—you can break it down. A to B, there’s one resistor- R. From B to X- there’s R/2. From Y to Z, there’s only R. Add these three and you’ll get 2.5R.

Variant 2:
(a) when all the switches are open, the resistance is always infinity.

When S1 is open and S2 is closed, two Rs are in series, which means R+R which is equal to 2R

When S1 is closed and S2 is closed, there are two parts there.
One circuit has two resistors in series—making 2R
the other circuit has two resistors is series—making 2R
both these circuits are in parallel with each other, so we use the 2R*2R/2R+2R or 1/2R+1/2R=1/Rt formula for the resistance which gives you just R as the answer.

Asamy111:
thnxxx .. can u plz explain the part B also  :)

halosh92:

--- Quote from: Asamy111 on June 08, 2010, 12:32:19 pm ---varient 1 .. bt still i ddnt gt hw to solve varient 2 too

--- End quote ---
ok
 c
first part its only one resistor so its only R thats simple ok
now between B and X
two resisotrs are in parallel ok?
so R*R/R+R
R^2/2R
simplify will give u R/2 which is nothing by 0.5R

now between A and Z:
view 0.5R as one resistor now u will have 3 resistor in series which will give u:
R + R + 0.5R
= 2.5R

ok got it?

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