In an experiment, electrons are accelerated, from rest, by applying a voltage of 500 V. Calculate the radius of the circular path if a magnetic field 100 mT is then applied.
[Charge of the electron, e = 1.6×10⁻¹⁹ C Mass of the electron, me = 9.1×10⁻³¹ kg]

A. 7.5×10⁻³ m
B. 7.5×10⁻² m
C. 7.5 m
D. 7.5×10⁻⁴ m