Question

Wavelength of an electron having energy 10 ke V is…….Å 

(A) 0.12 

(B) 1.2 

(C) 12 

(D) 120

Answer 1

The correct option is (A) 0.12.

Explanation:

λ = (h/p) = [h / √(3mE)]

given: E = 10 KeV = 10⁴ eV

i.e. E = 10⁴ × 1.6 × 10^–19 J

∴ λ = [{6.625 × 10^–34} / {√(2 × 9.1 × 10^–31 × 10⁴ × 1.6 × 10^–19)}]

= 0.12 × 10^–10 m

= 0.12 Å