# some body help me please

Discussion in 'Homework Help' started by qwertyuiopoiuytrewq, Oct 23, 2014.

Oct 10, 2014
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2. ### MrChips Moderator

Oct 2, 2009
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One post will do.

Mar 31, 2012
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4. ### qwertyuiopoiuytrewq Thread Starter New Member

Oct 10, 2014
16
1
I faced this question in an interview at a certain company but failed to solve. Could you please help me.

5. ### WBahn Moderator

Mar 31, 2012
20,245
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We can help you AFTER you show YOUR attempt to solve it. That will let us get a glimpse of what approach you are trying and where you are going right and where you are going wrong.

The bad news is that I suspect they were expecting you to be able to answer this question immediately and by inspection. But just telling you the answer won't help you learn the concepts that they wanted to know if you knew. So let's take it one step at a time.

In terms of the variables Vs, R1, R2, and RL, where Vs is the 100V supply and RL is the 50Ω load resistor, what is the power that is delivered to RL? Let's get that far and, once that is correct, we can proceed.

6. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,974
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You have four combinations of R1 and R2.

Case 1.
R1=0
R2=0
Assuming 50 Ohm is the load, solve for power.

Case 2.
R1=0
R2=100 Ohm
Assuming 50 Ohm is the load, solve for power.

Case 3.
R1=100 Ohm
R2=0
Assuming 50 Ohm is the load, solve for power.

Case 4.
R1=100 Ohm
R2=100 Ohm
Assuming 50 Ohm is the load, solve for power.

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7. ### WBahn Moderator

Mar 31, 2012
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The problem doesn't say that R1 and R2 are either 0Ω or 100Ω, it says that that are merely between those two values, inclusive, and he is supposed to find values that result in the maximum power possible delivered to the load.

At least that's the way I read the problem description.

8. ### atferrari AAC Fanatic!

Jan 6, 2004
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And who is the load? All off them are, I think.

9. ### shteii01 AAC Fanatic!

Feb 19, 2010
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617
It is actually pretty simple.

When R1=0 (R1 is short), 100 volts is across the load, that is when there is maximum power at the load.

Or you can crunch the numbers. "Pilot's choice."

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10. ### shteii01 AAC Fanatic!

Feb 19, 2010
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Yes, the wording is ambigious. It might be that they want three anwers: max power at 50 Ohm resitor, max power at R1, max power at R2.

11. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
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It is a trick question. Well, it is only a trick if you miss the point..., which I guess is the point...

12. ### qwertyuiopoiuytrewq Thread Starter New Member

Oct 10, 2014
16
1
in the question it is asked to find max power @ load resistance and the values of R1&R2 at maximum power at load

13. ### qwertyuiopoiuytrewq Thread Starter New Member

Oct 10, 2014
16
1
I tried to solve using thevenins theorem & maximum power transfer theorem but i failed to solve.Could you please help me.

Oct 10, 2014
16
1

15. ### qwertyuiopoiuytrewq Thread Starter New Member

Oct 10, 2014
16
1
I tried to solve using thevenins theorem & maximum power transfer theorem but i failed to solve.Could you please help me.

Oct 10, 2014
16
1

17. ### qwertyuiopoiuytrewq Thread Starter New Member

Oct 10, 2014
16
1

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18. ### Papabravo Expert

Feb 24, 2006
11,156
2,183
You need to show us what you have done. That is the only way we can help you. I don't understand why you keep repeating yourself.

19. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
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This could get laborious.
Perhaps the OP should read post #9. Almost the end of the story .... except for a statement concerning R2.....

20. ### WBahn Moderator

Mar 31, 2012
20,245
5,758
Then SHOW us your attempt to solve it that way. Go back and try using the approach I suggested in Post #5. You've been given plenty of hints that should lead you to see the solution by inspection, but the fact that you aren't seeing how to exploit them is a strong indicator that you will be best served by slugging through it. At some point you will have an, "Ah hah!" moment and see the light.

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