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# opearational amplifier problem

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Although this is one of those puzzles we don't encounter in real life, nevertheless there are seemingly impossible problems that come up.

Going strictly by the math...

The 6A is going away from ground, therefore output Vo is negative.
This limits the answer to A or C.

The 6k resistor has 6A going through it. So it has 36 kV across it ( 6 x 6k ).

Since the 6A current source must have some voltage drop, this means Vo is even further from zero than -36 kV.
So the 2k output resistor must carry current at an absolute value greater than 18A.
This means it cannot be answer A.

pforpashya

### pforpashya

Points: 2
Helpful Answer Positive Rating
Agreed !!! Vo = -36 KV so additional current through the 2 K going to earth = -18 A and the -6A -ve input current = -24 A?
Frank

pforpashya

### pforpashya

Points: 2
Helpful Answer Positive Rating
Although this is one of those puzzles we don't encounter in real life, nevertheless there are seemingly impossible problems that come up.

Going strictly by the math...

The 6A is going away from ground, therefore output Vo is negative.
This limits the answer to A or C.

The 6k resistor has 6A going through it. So it has 36 kV across it ( 6 x 6k ).

Since the 6A current source must have some voltage drop, this means Vo is even further from zero than -36 kV.
So the 2k output resistor must carry current at an absolute value greater than 18A.
This means it cannot be answer A.

Thanks for your reply,

they have solved and got -18A answer, but yes i think the options are wrong and -24A is the correct answer. can u suggest me a circuit simulator by which i can actually analyze circuit well? Thanks

they have solved and got -18A answer, but yes i think the options are wrong and -24A is the correct answer. can u suggest me a circuit simulator by which i can actually analyze circuit well? Thanks

I used Falstad's simulator (at falstad.com/circuit).

It confirms -24 A as the correct answer.

Screenshot:

I added the 10M resistor as a check to confirm that the output is referenced to zero ground.

Below is a link which will open the falstad.com website, load my schematic above, and run it on your computer. (Click Allow to permit the connection.)

https://tinyurl.com/anzke7f

pforpashya

### pforpashya

Points: 2
Helpful Answer Positive Rating
I used Falstad's simulator (at falstad.com/circuit).

It confirms -24 A as the correct answer.

Screenshot:

I added the 10M resistor as a check to confirm that the output is referenced to zero ground.

Below is a link which will open the falstad.com website, load my schematic above, and run it on your computer. (Click Allow to permit the connection.)

https://tinyurl.com/anzke7f

Thanks a lot for answering

- - - Updated - - -

just amazing tool thanks for sharing

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