Question

What is the wavelength of a beam of neutron having:
⦁ An energy of 0.025 eV?
⦁ An electron and photon each have wavelength of 2A°. what are their momentum and energy ? m_n = 1.676×10^-27 kg, h = 6.625×10^-34 J-sec. 

Answer 1

Given Data :-energy of neutron =0.025eV.
To find :-wavelength of a beam.

Calculation :-` λ=h/(√2meV)`

`=(6.626×10^(-34))/(√2×1.676×10^(-27) ×0.025×10^(-19) ×1.6)`

=1.8095A°.

Hence wavelength is equal to=1.8095A°.

2. Given Data :- λ=2A°,m_n =1.676×10^-27  kg,h= 6.625× 10^-34 J-sec.  

To find :- momentum and energy.

Calculations :- `λ =h/p` ,………………….(for momentum)

`2×10^(-10) = ( 6.625×10^(-34))/p`

P=3.3125×10^-24  kg-m/sec.

`λ=h/(√2mE)`

`2×10^(-10)  = (6.625×10^(-34))/(√2×1.676×10^(-27) ×)`

E = 5.721 × 10 ^-11 joules. 
Hence momentum=3.3125×10^-24 kg m/sec. and energy is=5.721×10^-11 joules.