Physics Olympiad question resistance and Electric circuit

[Hashiramasenju]

Homework Statement

In the fig all resistors have resistance R. If pd of V is applied across AB.

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)?

 

[mfb]

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.

 

[donpacino]

what is the potential difference between C and D

 

[Hashiramasenju]

what is the potential difference between C and D

zero

 

[Hashiramasenju]

So i understand that between C and D no current flows. So there is ans for 2)no change right ?

 

[donpacino]

So i understand that between C and D no current flows. So there is ans for 2)no change right ?

yup :)

 

[Hashiramasenju]

so is the current direction i marked correct ? and does current flow from o to d or d to o ?

 

[donpacino]

you won't know unless you know the resistor values... the real question, does the current direction you pick matter?

 

[mfb]

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.

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.