• Support PF! Buy your school textbooks, materials and every day products Here!

Equivalent Resistance

  • Thread starter MitsuShai
  • Start date
  • #1
159
0
The question was to rank from highest to lowest equivalent resistance. This is what I came up with, but it was counted wrong and I don't understand why.

http://i324.photobucket.com/albums/k327/ProtoGirlEXE/100_0687-1.jpg [Broken]

The equivalent resistance of resistors in series are added while in parallel the reciprocal is added.


Each resistor as the same R, so I used R=2

Here are my numbers, in the order that I ranked, wronging:

1. (1/2) + .5= 1 + 2= 3

2. 2

3. .5+ .5+ .5= 1.5

4. .5 + .5= 1

5. 2+2 = 4
(1/4)+ .5 = .75
 
Last edited by a moderator:

Answers and Replies

  • #2
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
9,033
2,416
It would be easier to troubleshoot your answers if you presented them in the order of the figures left to right. However, just by looking at what you have, I see no figure that shows two resistors in series corresponding to 2+2=4.
 
  • #3
1,137
0
3. .5+ .5+ .5= 1.5

5. 2+2 = 4
(1/4)+ .5 = .75
How have you done these??? they seems to be wrong
 
  • #4
1,137
0
I see no figure that shows two resistors in series corresponding to 2+2=4.
Its for upper part of last figure which he has done correctly

_________________

I guess you have solving parallel connections
 
  • #5
159
0
How have you done these??? they seems to be wrong[/QUOTE


Since R is equal in every resistor, I chose R=2


so for parallel the R is summed by the reciprocal (1/2)=.5
in series they are summed
 
  • #6
1,137
0
for parallel,

[tex]\frac{1}{R_{net}} = \frac{1}{R_1} + \frac{1}{R_2} \ ...[/tex]

so your answer is 1/(1.5)
 
  • #7
159
0
for parallel,

[tex]\frac{1}{R_{net}} = \frac{1}{R_1} + \frac{1}{R_2} \ ...[/tex]

so your answer is 1/(1.5)

Thank you so much for catching that error. I've looked over this problem many times to see if I was making an error, but I find it very hard to catch my own mistakes. :(
 

Related Threads on Equivalent Resistance

  • Last Post
Replies
3
Views
718
  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
2
Replies
30
Views
3K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
15
Views
1K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
9
Views
1K
Top