Physics Circle home Student Login

Home›Chapters›Dual Nature of Radiation and Matter PYQs›Matter Waves: de Broglie Wavelength›Question 125

JEE Main 2019 (8 Apr, Shift 2) · Matter Waves: de Broglie Wavelength

Matter Waves: de Broglie Wavelength question from JEE Main 2019 (8 Apr, Shift 2)

Q125JEE Main 2019 · 8 APR · SHIFT 2Difficult

Matter Waves: de Broglie Wavelength

A nucleus A, with a finite de-broglie wavelength λ\lambdaA, undergoes spontaneous fission into two nuclei B and C of equal mass. B flies in the same direction as that of A, while C flies in the opposite direction with a velocity equal to half of that of B. The de-Broglie wavelengths λ\lambdaB and λ\lambdaC of B and C are respectively:

Show answer and solution

Answer: (d)

  1. Let A have mass MM, speed vv; B and C have mass M/2M/2, velocities vBv_B and −vB/2-v_B/2.
  2. Momentum: Mv=M2vB−M2⋅vB2=M4vB⇒vB=4vMv = \dfrac{M}{2}v_B - \dfrac{M}{2}\cdot\dfrac{v_B}{2} = \dfrac{M}{4}v_B \Rightarrow v_B = 4v
  3. pB=2Mv=2pA⇒λB=λA2p_B = 2Mv = 2p_A \Rightarrow \lambda_B = \dfrac{\lambda_A}{2}; pC=M2(2v)=Mv⇒λC=λAp_C = \dfrac{M}{2}(2v) = Mv \Rightarrow \lambda_C = \lambda_A
  4. So the answer is (d).
Report a mistake

More questions on Matter Waves: de Broglie Wavelength