19.
(a) The frequency of revolution is
f =
Bq
2πm
e
=
(35.0
× 10
−6
T)(1.60
× 10
−19
C)
2π(9.11
× 10
−31
kg)
= 9.78
× 10
5
Hz .
(b) Using Eq. 29-16, we obtain
r =
m
e
v
qB
=
√
2m
e
K
qB
=
2(9.11
× 10
−31
kg)(100 eV)(1.60
× 10
−19
J/eV)
(1.60
× 10
−19
C)(35.0
× 10
−6
T)
= 0.964 m .