Calculating Effective resistance

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Homework Statement



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

Homework Equations


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)
 
Attachments
  • Circuit diagram: a triangle of black wire with a 2R resistor on its top side and 2R resistors on each slanting side, with two crossing wires running down to terminals labelled A and B, and a 2R resistor on each lower wire.
    physics.png
    6 KB · Views: 578
pratyushag said:

Homework Statement



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

Homework Equations



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)
Correct !
 
But why doesnot current enter if opp sides have equal amt of current
 
pratyushag said:
But why doesnot current enter if opp sides have equal amt of current

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.
 
Attachments
  • Circuit schematic of a series-parallel resistor network on a horizontal wire: a 2R resistor on the left and another 2R on the right, with a bridge of three 2R resistors (two vertical, one horizontal on top) connected between two nodes on the main wire.
    resi.png
    890 bytes · Views: 518
There is no potential difference across those 3 resistors in the "loop".
 
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pratyushag said:
But why doesnot current enter if opp sides have equal amt of current

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.
 
pratyushag said:
Why do the resistors short?

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.
 
Attachments
  • Line diagram of a circuit-style wire layout: a horizontal wire along the bottom and an inverted V-shaped wire above, meeting at a point on the bottom wire, with red dots marking nodes at the top, both sides, and bottom ends.
    Morph1.jpg
    7.7 KB · Views: 485
  • Hand-drawn style circuit diagram: a trapezoid of black wire with a horizontal top, two slanted sides meeting a horizontal line below, with red dots marking connection points of varying sizes.
    Morph2.jpg
    8.2 KB · Views: 518
  • Hand-drawn circuit diagram: a rectangular black wire loop sits on a horizontal black wire, with red dots marking nodes at the top, left side, right side, and bottom left and bottom right of the lower line.
    Morph3.jpg
    5.9 KB · Views: 522
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