 #1
Andrei0408
 50
 8
 Homework Statement:
 I need to calculate the equivalent resistance in 4 different cases
 Relevant Equations:

1/Rep = 1/R1 + 1/R2 + ... + 1/Ri
Res = R1 + R2 + ... + Ri
R1 = 2 ohms ; R2 = 2 ohms; R3 = 1ohm
First figure:
I need to calculate the resistance between: a) A and C and b) A and B
a) R1 and R3 are in series => R13 = R1 + R3 = 3 ohms
R13 and R2 are in parallel => 1/Rp = 1/R13 + 1/R2 => Rp = 1.2 ohms
b) Here, between A and B there is only R1 so the equivalent resistance will be 1 ohm? (is this correct?)
Second figure:
I need to calculate the resistance between: a) A and C and b) B and C
a) R1 and R3 are in series => Rs = R1 + R3 = 3 ohms
But here, if we take another path: R1 and R2 parallel the result will be 1 ohm.
Which one is correct and why are they different?
b) Between B and C there is only R3 = 1 ohm.
But if we take R2 parallel with R3 => 0.66 ohms
Which one is correct?
Third figure:
I need the resistance between A and D:
R1 and R3 are in series => R1+R3 = 3 ohms
Fourth figure:
I need the resistance between A and D:
Here couldn't I take the same path as earlier and get 3 ohms or the path with R2 only for 2 ohms?
Could you please explain where I'm wrong and which one is the correct answer at each point? Thank you, in advance!
First figure:
I need to calculate the resistance between: a) A and C and b) A and B
a) R1 and R3 are in series => R13 = R1 + R3 = 3 ohms
R13 and R2 are in parallel => 1/Rp = 1/R13 + 1/R2 => Rp = 1.2 ohms
b) Here, between A and B there is only R1 so the equivalent resistance will be 1 ohm? (is this correct?)
Second figure:
I need to calculate the resistance between: a) A and C and b) B and C
a) R1 and R3 are in series => Rs = R1 + R3 = 3 ohms
But here, if we take another path: R1 and R2 parallel the result will be 1 ohm.
Which one is correct and why are they different?
b) Between B and C there is only R3 = 1 ohm.
But if we take R2 parallel with R3 => 0.66 ohms
Which one is correct?
Third figure:
I need the resistance between A and D:
R1 and R3 are in series => R1+R3 = 3 ohms
Fourth figure:
I need the resistance between A and D:
Here couldn't I take the same path as earlier and get 3 ohms or the path with R2 only for 2 ohms?
Could you please explain where I'm wrong and which one is the correct answer at each point? Thank you, in advance!