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MHT CET 2024 (3 May, Shift 2) · Electrostatic Potential Energy

Electrostatic Potential Energy question from MHT CET 2024 (3 May, Shift 2)

Q35MHT CET 2024 · 3 MAY · SHIFT 2Medium

Electrostatic Potential Energy

Two charged particles each having charge ' qq ' and mass ' mm ' are held at rest while their separation is ' rr '. The speed of the particles when their separation is ' r2\frac{r}{2} ' will be ( ε0=\varepsilon_0 = permittivity of the medium)

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Answer: (c)

  1. Loss in PE: ΔU=q24πε0(2r−1r)=q24πε0r\Delta U = \frac{q^2}{4\pi\varepsilon_0}\left(\frac{2}{r} - \frac{1}{r}\right) = \frac{q^2}{4\pi\varepsilon_0 r}
  2. Both particles move with equal speed: total KE =2⋅12mv2=mv2= 2\cdot\frac{1}{2}mv^2 = mv^2.
  3. mv2=q24πε0r⇒v=q4πε0mrmv^2 = \frac{q^2}{4\pi\varepsilon_0 r} \Rightarrow v = \frac{q}{\sqrt{4\pi\varepsilon_0 mr}}
  4. So the answer is (c).
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