question_answer

An electron emitted from a hot filament is accelerated through a potential difference    of 2.88 kV and enters a region of a uniform magnetic field \[0.\pi \]at an angle of \[{{30}^{o}}\] with the field. Take the mass of an electron \[9\times {{10}^{-31}}\] kg. The trajectory of the electron is

A)  Circle of radius 1.6 mm

B)  Circle of radius 0.9 mm

C)  Helix of radius 0.9 mm

D)  Helix of radius 1.6 mm