Q.


An expression for de Broglie wavelength of matter waves is:


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a

λ=hp

b

λ=h2p

c

λ=h4p

d

None of these 

answer is A.

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Detailed Solution

Concept- We'll start by comparing Einstein's equation connecting matter and energy with Planck's equation, with the assumption that the energies in both cases are equal.
Formulas Used: Question Image and Question ImageDe Broglie obtained his equation using well-known ideas by making the following substitutions:
Einstein's famous equation connecting matter and energy states that
Question Image where Question Image denotes energy, Question Image denotes mass and Question Image denotes the speed of light
Using Planck's theory which states every quantum of a wave has a discrete amount of energy given by Planck's equation
Question Image where Question Image denotes the energy, Question Image denotes the planck's constant and Question Image denotes the frequency
The value of the planck's constant is given by Question Image Joule-sec
Because physical particles do not travel at the speed of light, de Broglie substituted v for the particle's velocity for the speed of light (c)
We can solve the equation (1) by replacing c with v.
Question ImageDe Broglie theorised that because particles and waves had the same properties, their energy would be equal.
The LHS of both equations (2) and (3) is clearly the same (i.e., energy E). As a result, the RHS of both equations may be equaled and will be equal.
Question ImageQuestion ImageQuestion ImageWe can write anything based on the relationship between the wavelength, velocity, and frequency of any wave.
Question ImageBy substituting Question Image in equation (4), we get
Question ImageQuestion ImageQuestion ImageAs we know that the momentum Question Image is the product of mass Question Image and the velocity Question Imagei.e., Question ImageWe get by inserting p = mv in equation (5).
Question Image where Question Image denotes de Broglie wavelength of matter waves, Question Image is planck's constant (
Question Image Joule-sec) and Question Image denotes the momentum of the matter wave.
The above equation is the necessary expression for the de Broglie wavelength of matter waves.
Hence, the correct answer is option 1.
 
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