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QJEEM19Ph273a: JEE Main 2019 Physics - Class 12 JEEM19Ph273a Solution: Two electric dipoles, A, B with respective dipole moments and…

Two electric dipoles, A, B with respective dipole moments d→A=−4qai{\overrightarrow d _A} = - 4qai and d→B=−2qai{\overrightarrow d _B} = - 2qai are placed on the x-axis with a separation R, as shown in the figure. The distance from A at which both of them produce the same potential is -

JEE Main 2019 (Online) 10th January Morning Slot Physics - Electrostatics Question 183 English

Multiple Choice Options

  • A 2R2+1{{\sqrt 2 R} \over {\sqrt 2 + 1}}
  • B R2+1{R \over {\sqrt 2 + 1}}
  • C 2R2−1{{\sqrt 2 R} \over {\sqrt 2 - 1}}
  • D R2−1{R \over {\sqrt 2 - 1}}

Step-by-Step Verified Solution

V =4qa(R+x)=2qa(x2)= {{4qa} \over {\left( {R + x} \right)}} = {{2qa} \over {\left( {{x^2}} \right)}}

2x=R+x\sqrt 2 x = R + x

x=R2−1x = {R \over {\sqrt 2 - 1}}

JEE Main 2019 (Online) 10th January Morning Slot Physics - Electrostatics Question 183 English Explanation
dist =R2−1+R=2R2−1= {R \over {\sqrt 2 - 1}} + R = {{\sqrt 2 R} \over {\sqrt 2 - 1}}

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