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Concepts Of Physics MCQ Edition [Volume 2]PhysicsElectric Current in Conductors

Determine the equivalent resistance between the points a and b for the circuits displayed in the figure. Every resistor has a resistance r .

Options

  1. A(a) r 2 , (b) 4r 5
  2. B(a) 2r 3 , (b) 4r 5
  3. C(a) r 2 , (b) 5r 4
  4. D(a) r 3 , (b) 5r 6

Correct answer

A. (a) r 2 , (b) 4r 5

Step-by-step solution

For the first circuit, let the vertices of the triangle be a , b , and c (top), and the central node be o . The circuit is symmetric about the vertical axis passing through c and o . When a potential difference is applied across a and b , the nodes c and o will be at the same potential. Since V_c = V_o , no current flows through the resistor connecting c and o , so it can be removed from the circuit. The simplified circuit consists of three parallel branches between a and b . The first branch is the direct resistor

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