Verified Solution • 2025–26 Session moderate

QJEEM21Ph4796: JEE Main 2021 Physics - Class 12 JEEM21Ph4796 Solution: A moving proton and electron have the same de-Broglie…

A moving proton and electron have the same de-Broglie wavelength. If K and P denote the K.E. and momentum respectively. Then choose the correct option :

Multiple Choice Options

  • A Kp < Ke and Pp = Pe
  • B Kp = Ke and Pp = Pe
  • C Kp < Ke an Pp < Pe
  • D Kp > Ke and Pp = Pe

Step-by-Step Verified Solution

λp=hPp{\lambda _p} = {h \over {{P_p}}}

λe=hPe{\lambda _e} = {h \over {{P_e}}}

∵\because λp=λe{\lambda _p} = {\lambda _e}

⇒Pp=Pe\Rightarrow {P_p} = {P_e}

(K)p=Pp22mp{(K)_p} = {{P_p^2} \over {2{m_p}}}

(K)e=Pe22me{(K)_e} = {{P_e^2} \over {2{m_e}}}

Kp < Ke as mp > me

Option (a)

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