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JEE Main 202131 AugustEvening Shift
Exam
JEE Main
Year
2021
Date
31 August
Shift
Evening Shift
Subject
Physics
Chapter
Dual Nature of Matter

JEE Main 2021 · 31 August · Evening Shift · Physics · Dual Nature of Matter

Consider two separate ideal gases of electrons and protons having...

Consider two separate ideal gases of electrons and protons having same number of particles. The temperature of both the gases are same. The ratio of the uncertainty in determining the position of an electron to that of a proton is proportional to:

Options

  1. Ampme\sqrt{\dfrac{{m}_{p}}{{m}_{e}}}
  2. Bmpme\dfrac{{m}_{p}}{{m}_{e}}
  3. C(mpme)32\left(\dfrac{{m}_{p}}{{m}_{e}}\right)\dfrac{3}{2}
  4. Dmemp\sqrt{\dfrac{{m}_{e}}{{m}_{p}}}

Correct answer

A. mpme\sqrt{\dfrac{{m}_{p}}{{m}_{e}}}

Step-by-step solution

K.E.=32kTK . E . = \dfrac{3}{2}kT
⇒p22m=32kT⇒ \dfrac{{p}^{2}}{2m} = \dfrac{3}{2}kT
⇒p=3kTm⇒ p = \sqrt{3kTm}
From Heisenberg uncertainty principle
∴\Deltax\Deltap=h4π∴ \Deltax\Deltap = \dfrac{h}{4\pi}
\Deltax=h4π\Deltap=h4π3kTm\Deltax = \dfrac{h}{4\pi\Deltap} = \dfrac{h}{4\pi\sqrt{3kTm}}
∴\Deltax∝1m∴ \Deltax ∝ \dfrac{1}{\sqrt{m}}
∴ΔxeΔxp=mpme∴ \dfrac{\Delta{x}_{e}}{\Delta{x}_{p}} = \sqrt{\dfrac{{m}_{p}}{{m}_{e}}}
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