Electronics question

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2nd February 2008, 08:57am
#1
by Lord-Svenstikov
Worcester United Kingdom
Member Since: Sep 2007
Member Points: 727

I know that there are a fair few people on this website who know their physicsy stuff so I would like this out.

Now I know that the formula for adding resistances that are in parrallel is:

1/R(total)=1/R(1)+1/R(2)+1/R(3)...

(Brackets denote subscript)

Now I would like to bring to the topic superconducters which operate with zero resistance. Now logically if you put a path of zero resistance in parrallel with a resistor, of say 1 ohm, then the overall resistance will be zero also.

However the equation breaks down.

1/R(total)=1/1+1/0

Do we just have to asume that the resistance is infinately close to zero?

I wish things would stick to the rules in life.


2nd February 2008, 09:24am
#2
by Daemon_Panda
Coconut Grove , Fl United States
Member Since: Jun 2007
Member Points: 1043
I think so...
2nd February 2008, 09:59am
#3
by ulapayi
alicante Spain
Member Since: Jul 2007
Member Points: 92

If there are no resistance value why d´you want to put it in

a resistance formula???  Undecided


2nd February 2008, 11:04am
#4
by Lord-Svenstikov
Worcester United Kingdom
Member Since: Sep 2007
Member Points: 727

Even though it has a resistance value equal to zero, it still has a resistance value so I thought it would work.

Can someone explain why it doesn't work?


2nd February 2008, 11:09am
#5
by Unbeliever
United States
Member Since: Nov 2007
Member Points: 1119
You have to assume the resistance is the limit as it approaches zero.
2nd February 2008, 11:24am
#6
by Unbeliever
United States
Member Since: Nov 2007
Member Points: 1119
I suppose we could theoretically achieve a resistance of Zero if we reached Absolute Zero, but I may be wrong.
2nd February 2008, 12:56pm
#7
by Daemon_Panda
Coconut Grove , Fl United States
Member Since: Jun 2007
Member Points: 1043

we have nearly acheived that.

If I remember the article in Pop Sci (Popular Science) we are .118 away from absolute zero.


2nd February 2008, 01:01pm
#8
by Daemon_Panda
Coconut Grove , Fl United States
Member Since: Jun 2007
Member Points: 1043
Funny, I'm just watching WLRN and I found out that within the next few days they will be showing something on absolute zero.
3rd February 2008, 02:08am
#9
by Lord-Svenstikov
Worcester United Kingdom
Member Since: Sep 2007
Member Points: 727

I'm glad that it doesn't have a resistance of 0, it is only really close. It makes me feel nice and safe to have the mathematical laws of universe working again.

Thank you for the information people.


3rd February 2008, 07:20am
#10
by Alex_M
Atlanta, Georgia United States
Member Since: Nov 2007
Member Points: 266
Daemon_Panda wrote:

we have nearly acheived that.

If I remember the article in Pop Sci (Popular Science) we are .118 away from absolute zero.


I don't recall reading that. .118 degrees I assume. Celcius or Farenheit?


6th February 2008, 11:45pm
#11
by sirfraijo
Mesa United States
Member Since: Dec 2007
Member Points: 61

1/Rt = 1/R1+1/R2+...1/Rt

Rt=0=R1...R2....

Rt/1= 1/(1/R1...+1/Rt)

0/1=0     1/(infinite)=0

 That 1 in parallel doesn't affect to the infinite.

 


 

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