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MODEL PAPER 8 — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsMODEL PAPER 81 Mark
MCQ
Assertion (A): de-Broglie wavelength is significant for microscopic particles.
Reason (R): de-Broglie wavelength is inversely proportional to the mass of a particle when velocity is kept constant.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true.
✓

Answer

(a) Both A and R are true and R is the correct explanation of A. 
Explanation: de-Broglie wavelength, $\lambda=\frac{h}{m v}$ 
h and v remaining constant, $\lambda \propto \frac{1}{m}$
So, as the mass of the particle becomes smaller and smaller the de-Broglie wavelength of the particle becomes more and more significant.
Hence, assertion and reason both are true and reason explains the assertion properly.

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