The Solution Manual says that "The bottom four resistors 'between 2 ohm resistor and the source voltage of 30v' are SHORTED OUT " . How we can tell ? Kindly Exp lain. THanks!

 

hi hunter,
What do you calculate the resistance to be between the -30v and the 2 Ohm.?
E

 

hi hunter,
What do you calculate the resistance to be between the -30v and the 2 Ohm.?
E

6 || 2 + 13 || 12 = 7.74 ohms

 

Look at this image, what do you make it now.?
E

 

Look at this image, what do you make it now.?
E
View attachment 147507

I make it 7.74 ohms , by the above calculation

 

Hello,

And what would be the effect of the 0 Ohms short on your calculations?

Bertus

 

Put 0 Ohms in parallel with your answer, it cannot be 7.74 Ohms,???

 

Notice that there is a direct path (0 ohms wire resistance) for a current between points A and B.

 

Notice that there is a direct path (0 ohms wire resistance) for a current between points A and B.
View attachment 147509

Thanks ! I got it

 

Th

Put 0 Ohms in parallel with your answer, it cannot be 7.74 Ohms,???

Thanks ! I got it

 

6 || 2 + 13 || 12 = 7.74 ohms

Remove the short that you didn't take into account here and this would still be wrong.

For two components (or circuits) to be in parallel, you have to have the SAME voltage across them.

While the 6 Ω and 2 Ω resistors have the same voltage on the left side of them, the voltage on the right side of the 6 Ω resistor is NOT the same as the voltage on the right side of the 2 Ω resistor.