Question

The wavelength of a neutron with energy 1 eV is closest to –

• A. 10^–2 cm
• B. 10^–4 cm
• C. 10^–6 cm
• D. 10^–8 cm

Answer 1

Answer: (D)

10^–8 cm

Answer 2

The wavelength l of a particle of momentum p is

l =$\frac{h}{p}$=$\frac{h}{\sqrt{2mE}}$=$\frac{h}{\sqrt{2mc^{2}E}}$=$\frac{4.14 \times 10^{- 15} \times 3 \times 10^{8}}{\sqrt{2} \times 940 \times 10^{6}}$

= 2.9 × 10^–11 m.