NEETPhysicsAtomic Physics
Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : In Davisson-Germer experiment wavelength associated with the beam decreases with increases of speed of electrons. Reason (R) : Wavelength associated with electron beam in Davission-Germer experiment is given by ( = h 2 mK ) In the light of the above statements, choose the most appropriate answer f
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A).
- BBoth (A) and (R) are true and (R) is NOT the correct explanation of (A).
- C(A) is true but (R) is false.
- D(A) is false but (R) is true.
Correct answer
C. (A) is true but (R) is false.
Step-by-step solution
- Assertion (A): In the Davisson-Germer experiment, the wavelength associated with the electron beam indeed decreases with the increase in the speed of electrons. This follows from de Broglie's equation, ( = h m v ), where (v ) is the speed of the electrons. As the speed increases, the wavelength decreases, making the assertion true. - Reason (R): The equation ( = h 2 m K ) is incorrect. The correct form of de Broglie's wavelength is ( = h p ) where (p=m v ) is the momentum of the electron, or ( = h 2 m E_k ), wher