Physics Olympiad question resistance and Electric circuit

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SUMMARY

The discussion centers on a Physics Olympiad question involving an electric circuit with resistors of resistance R and a potential difference V applied across points A and B. Key points include that connecting points C and D results in no current flow, effectively creating a short circuit, which leads to no change in potential difference across CO. The resistance across A and B can be calculated using the formula 1/∑R=1/R1 +1/R2, while the resistance across AO requires further analysis based on the circuit configuration.

PREREQUISITES
  • Understanding of Ohm's Law (V=IR)
  • Familiarity with series and parallel resistor combinations
  • Basic knowledge of electric circuits and current flow
  • Ability to analyze circuit diagrams
NEXT STEPS
  • Study the principles of series and parallel circuits in depth
  • Learn how to apply Kirchhoff's laws in circuit analysis
  • Explore the concept of equivalent resistance in complex circuits
  • Practice solving problems involving short circuits and open circuits
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Students preparing for Physics Olympiads, educators teaching electric circuit concepts, and anyone interested in enhancing their understanding of circuit analysis and resistance calculations.

Hashiramasenju
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Homework Statement


In the fig all resistors have resistance R. If pd of V is applied across AB.
upload_2015-11-12_7-39-12.jpeg


1)What is the outcome of joining C and D
2)Whats is the pd across CO
3)what is the resistance across A and B
4)What is the resistance across AO

Homework Equations


V=IR
1/∑R=1/R1 +1/R2

The Attempt at a Solution


So for
1) i thought that it would cause a short circuit because instead of flowing through the resistors co &od it would directly flow.
2)?
3)?
4)?
 
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Hashiramasenju said:
1) i thought that it would cause a short circuit because instead of flowing through the resistors co &od it would directly flow.
What would flow from where to where? You are connecting C and D, not E and F.
 
what is the potential difference between C and D
 
donpacino said:
what is the potential difference between C and D
zero
 
So i understand that between C and D no current flows. So there is ans for 2)no change right ?
 
Hashiramasenju said:
So i understand that between C and D no current flows. So there is ans for 2)no change right ?
yup :)
 
so is the current direction i marked correct ? and does current flow from o to d or d to o ?
 
you won't know unless you know the resistor values... the real question, does the current direction you pick matter?
 
As currents can be negative, you can draw the arrows in any direction you like. One direction will lead to positive current, one to negative current - unless the current is zero of course.
Hashiramasenju said:
So i understand that between C and D no current flows. So there is ans for 2)no change right ?
Correct. How did you figure that out? A proper description will help with the next part.
 

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