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MHT CET 2023 (12 May, Shift 2) · Electrostatic Potential Energy

Electrostatic Potential Energy question from MHT CET 2023 (12 May, Shift 2)

Q39MHT CET 2023 · 12 MAY · SHIFT 2Medium

Electrostatic Potential Energy

Three point charges +Q,+2q+Q, +2q and +q+q are placed at the vertices of a right angled isosceles triangle. The net electrostatic potential energy of the configuration is zero, if QQ is equal to

Figure

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Answer: (a)

  1. Q is at the right angle: legs aa, hypotenuse 2a\sqrt2 a.
  2. U=k[2qQa+qQa+2q22a]=0U = k\left[\dfrac{2qQ}{a} + \dfrac{qQ}{a} + \dfrac{2q^2}{\sqrt2 a}\right] = 0
  3. 3Q=−2q⇒Q=−23q3Q = -\sqrt2 q \Rightarrow Q = -\dfrac{\sqrt2}{3}q
  4. So the answer is (a).
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