Need help in Aptitude Question

WBahn

Joined Mar 31, 2012
32,870
Here it is:

The equivalent resistance, Req, of two resistors R1 and R2, placed in parallel is given by

\(
R_{eq} \: = \: \frac{R_1 \cdot R_2}{R_1 \: + \: R_2}
\)

Show that, if R1 ≤ R2, then

Req ≤ R1

and that

(R1)/2 ≤ Req ≤ (R2)/2

NOTE: I added a lower limit to the last one.

This is a very useful result as it allows you to place bounds on the equivalent resistance of parallel resistors (or inductors, or series capacitors) by inspection. And we've seen how useful bounds can be.
 
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WBahn

Joined Mar 31, 2012
32,870
Then why don't you join a forum in your own language? If you don't understand English then you shouldn't be on an English-speaking forum.
I don't mind that, too much. If I were trying to learn Chinese (which, given my marital situation, is something I would very much love to do) I would look to join Chinese-language forums at some point to help improve my proficiency -- and I'm sure I would be a constant source of frustration for those trying to interact with me.

But I have wondered frequently what the situation is with regard to decent electronics-oriented forums in other languages. I haven't shopped around, but based on what you and others mention from time to time, it seems like the number of decent English-language forums is pretty limited.
 

DerStrom8

Joined Feb 20, 2011
2,390
I don't mind that, too much. If I were trying to learn Chinese (which, given my marital situation, is something I would very much love to do) I would look to join Chinese-language forums at some point to help improve my proficiency -- and I'm sure I would be a constant source of frustration for those trying to interact with me.

But I have wondered frequently what the situation is with regard to decent electronics-oriented forums in other languages. I haven't shopped around, but based on what you and others mention from time to time, it seems like the number of decent English-language forums is pretty limited.
I get the sense he has no interest in learning the English language, only getting answers. Therefore, he's just wasting everyone's time.
 

WBahn

Joined Mar 31, 2012
32,870
He's actually been putting in some effort, though it has been painful for everyone involved (including him!). He has indicated that he has trouble staying focused. I've known several people like that (lots of people with mild versions of it, but a handful with really serious problems). As long as he's willing to continue trying, I'm willing to continue helping. In the end it may not improve his technical skills much, but it might help him learn to focus a bit better, which would possibly be the bigger win.
 
I get the sense he has no interest in learning the English language, only getting answers. Therefore, he's just wasting everyone's time.
I respectfully disagree -- I feel he has shown and is continuing to show both genuine effort and progress!:) -- Moreover, I draw your attention to the fact that the exercises are now provided by us (i.e. @WBahn and myself) hence, IMO, his continued interest has demonstrated his 'honorable intentions' as it were...

Very best regards
HP:)
 
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