An α -particle moves in a circular path of radius 1 cm in a uniform magnetic field of 0.125 T. The de-Broglie wavelength associated with the α- particle is
a. 1.65×10⁻¹²m
b. 3.3×10⁻¹²m
c. 4.95×10⁻¹²m
d. 6.6×10⁻¹²m