# Homework Help: Calculating Effective resistance

1. Nov 15, 2012

### pratyushag

1. The problem statement, all variables and given/known data

In the given circuit,the equivalent resistance between points A and B will be?

2. Relevant equations

3. The attempt at a solution
My solution

Effective resistance will be 2Ω+2Ω=4Ω as the current will not enter the triangle as equal amt of current enter from opposite sides(Im not sure about this part)

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2. Nov 15, 2012

### SammyS

Staff Emeritus
Correct !

3. Nov 15, 2012

### pratyushag

But why doesnot current enter if opp sides have equal amt of current

4. Nov 15, 2012

### Saitama

Not sure what do you mean by "opp sides". If you redraw the circuit (see attachment), the three resistors short and no current flows through them.

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5. Nov 15, 2012

### pratyushag

Why do the resistors short?

6. Nov 15, 2012

### SammyS

Staff Emeritus
There is no potential difference across those 3 resistors in the "loop".

Last edited: Nov 15, 2012
7. Nov 15, 2012

### bsbs

there is current in the loop that arrive at the same node, but the current is negligible. meaning not worth mentioning.

if you take one part of the loop at the same node to connect after the resistor near B, thereby creating another node, current that enters that series of 3 x 2Ω will meet at another node, this created a potential difference, and usually with p.d. and resistance, you can work out the I.

8. Nov 15, 2012

### CWatters

because there is a physical short circuit shown in your original circuit.

The drawing produced by Pranav-Arora is electrically the same as yours just a different physical shape. He's not added any wire or nodes just changed the physical shape of the existing node.

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Last edited: Nov 15, 2012