A beam of protons with speed 4 × 10⁵ ms^–1
enters a uniform magnetic field of 0.3 T at an
angle of 60° to the magnetic field. The pitch of
the resulting helical path of protons is close to :
(Mass of the proton = 1.67 10^–27 kg, charge
of the proton = 1.69 10^–19 C)