Using complex numbers to solve for a current in this circuit

In summary: Precise.In summary, the OP is trying to solve an equation for current in a circuit, but he can't seem to get it right. He started with a complex number and simplified it down to 5. Then he plugged it back in to the original equation and got the correct answer.
  • #36
GJ1 said:
Can you just explain how you get 50/2+j from 150/(4+j)+2
He doesn't. He gets 50/(2+j) from 150/( (4+j3)+2 ).
Please use parenthesis to make your math expressions clear.

This is not just a picky complaint. In these days of computers and calculators, they will always give you the wrong answer if the parenthesis are wrong.
 
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  • #37
Just got it. Thanks for explaining it with your example. Greatly appreciated!!!!!
 
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  • #38
PeroK said:
And yet:
$$\bigg [\frac{50}{(4 + j3)(50) + 100} \bigg ] \times 150 = \frac{150}{(4 + j3) + 2}= \frac{50}{2+ j} = \frac{(50)(2 - j)}{5} = 20 - j10 $$
I stand corrected.
 
  • #39
FactChecker said:
He doesn't. He gets 50/(2+j) from 150/( (4+j3)+2 ).
Please use parenthesis to make your math expressions clear.

This is not just a picky complaint. In these days of computers and calculators, they will always give you the wrong answer if the parenthesis are wrong.
Understood
 
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  • #40
Mark44 said:
I stand corrected.
And now the OP has what he wanted. A solution on a plate!
 
  • #41
PeroK said:
And now the OP has what he wanted. A solution on a plate!
Right. But it won't go very far unless the OP has learned from this thread. Still, we should be careful to not give in to frustration and just give the answer.
 
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  • #42
FactChecker said:
Right. But it won't go very far unless the OP has learned from this thread.
We could give them a similar complex number manipulation question to test their understanding. Any volunteers? :smile:
 
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  • #43
GJ1 said:
It's (50/(4+j3)(50)
Those parentheses do not match up. You are missing a "closing paren" somewhere. I'm having a little trouble guessing what the 50 over (4+j3) represents. What about the second 50? Some units would be nice.
 

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