Answer:
4.4 cm
Explanation:
B = 1.98 mT = 1.98 x 10^-3 T, v = 1.53 x 10^7 m/s, m = 9.1 x 10^-31 kg
q = 1.6 x 10^-19 C
(a) The force due to the magnetic field is balanced by the centrpetal force
mv^2 / r = q v B
r = m v / q B
r = (9,1 x 10^-31 x 1.53 x 10^7) / (1.98 x 10^-3 x 1.6 x 10^-19)
r = 0.044 m = 4.4 cm