Answer
Given,
Magnetic field, B = 0.0000193 T
speed, v = 121 m/s
mass of electron, m = 9.11 x 10⁻³¹ Kg
charge of electron, q = 1.6 x 10⁻¹⁹ C
radius of the electron path, r = ?
r = 3.64 x 10⁻⁵ m
We know frequency is inverse of time period
d = v t
t = 1.889 x 10⁻⁶ s.
now, frequency