Q. An α-particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb/m². The de Broglie wavelength associated with the particle will be
A) 0.01 Å
B) 1 Å
C) 0.1 Å
D) 10 Å
Explanation
[Solution from source] In a magnetic field, momentum p = qBr with q = 2e for an α-particle. λ = h/(2eBr) = 6.63 × 10⁻³⁴/(2 × 1.6 × 10⁻¹⁹ × 0.25 × 0.83 × 10⁻²) ≈ 1.0 × 10⁻¹² m = 0.01 Å. Taking the charge as e instead of 2e doubles the wavelength. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.