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JEE MainPhysicsCurrent Electricity

Three wires meet at a central junction O . The other ends of the wires are connected to points A , B , and C . The potentials at points A and B are 50 V and 10 V respectively. The resistances of the branches connected to A , B , and C are 10 , 5 , and 15 respectively. If the current in the branch connected to C is 1.0 A flowing from the junction O towards point C , the potential at point C is

Options

  1. A42 V
  2. B8 V
  3. C35 V
  4. D5 V

Correct answer

D. 5 V

Step-by-step solution

Let the potential at the junction O be V_O . According to Kirchhoff's Current Law at junction O , the sum of currents arriving from A and B must equal the current leaving towards C . V_A - V_O R_A + V_B - V_O R_B = I_C Substituting the given values: 50 - V_O 10 + 10 - V_O 5 = 1.0 Multiplying the entire equation by 10 : (50 - V_O) + 2(10 - V_O) = 10 50 - V_O + 20 - 2V_O = 10 70 - 3V_O = 10 3V_O = 60 V_O = 20 V The current flows from O to C , so by Ohm's law for branch C : V_O - V_C = I_C R_C 20 - V_C = 1.0 15 V_C =

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