Practice problem: Determining R using current divider method

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Discussion Overview

The discussion revolves around a practice problem involving the determination of a load resistor (R_L) using the current divider method. Participants are analyzing the results of their calculations and comparing them with a textbook answer, which has led to confusion regarding the correct value of R_L.

Discussion Character

  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant calculates that the current through a 10-ohm resistor is 0.2 amperes and through R_L is 0.25 amperes, leading to a conclusion that R_L is 8 ohms, while the textbook states it should be 24 ohms.
  • Another participant confirms the calculation of R_L as 8 ohms, noting that this value results in an output voltage of 2V.
  • Some participants express skepticism about the textbook answer, suggesting it may be an error, while others are unsure how the textbook arrived at 24 ohms.

Areas of Agreement / Disagreement

Participants generally disagree on the correct value of R_L, with multiple participants supporting the calculation of 8 ohms, while the textbook answer remains contested.

Contextual Notes

There is uncertainty regarding the interpretation of the problem and the assumptions made in the calculations. The discussion does not resolve the discrepancy between the calculated and textbook values.

Who May Find This Useful

Readers interested in circuit analysis, current divider methods, and practical problem-solving in electrical engineering may find this discussion relevant.

Saeed.z
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Hi all ,

there is a practice problem in my textbook which say :

http://im17.gulfup.com/2012-02-14/1329248560881.jpg

i found after the load is attached that the current through 10 ohm's is 0.2 ampere and through R_L is 0.25 ampere, therefore , the value of R_L is 8 ohm's but the correct answer is 24 ohm's !

i checked again with the multism program and found my answer is correct !

i used the current divider method here .

so I'm a little confused ! which one is correct ?

BTW , sorry for my bad english :)

thanks

 
Last edited by a moderator:
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Saeed.z said:
Hi all ,

there is a practice problem in my textbook which say :

http://im17.gulfup.com/2012-02-14/1329248560881.jpg

i found after the load is attached that the current through 10 ohm's is 0.2 ampere and through R_L is 0.25 ampere, therefore , the value of R_L is 8 ohm's but the correct answer is 24 ohm's !

i checked again with the multism program and found my answer is correct !

i used the current divider method here .

so I'm a little confused ! which one is correct ?

BTW , sorry for my bad english :)

thanks


The current drawn from the source power supply is greater when the Rl resistor is connected.

To figure this out, just write the equation for the output voltage with the known resistors 40 and 10 and the unknown Rl in parallel with the 10 Ohm resistor.
 
Last edited by a moderator:
I get 8 Ohms too.
 
DragonPetter said:
I get 8 Ohms too.

Interesting. I didn't even bother to figure out the answer, but you are right. Plugging in 8 Ohms for the load resistor does give 2V at the output. Hmm...
 
berkeman said:
Interesting. I didn't even bother to figure out the answer, but you are right. Plugging in 8 Ohms for the load resistor does give 2V at the output. Hmm...

I tried to figure out where they could get 24 ohms from, as if I misinterpreted the problem, but I didn't bother with spending the time and assume its an error in the answer book.
 
@berkeman
@DragonPetter
thank you all of you guys , i really appreciate your help !
thanks !
 

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