75.
(a) We use Eq. 29-16 to calculate r:
r =
m
e
v
qB
=
(9.11
× 10
−31
kg)(0.10)(3.00
× 10
8
m/s)
(1.60
× 10
−19
C)(0.50 T)
= 3.4
× 10
−4
m .
(b) The kinetic energy, computed using the formula from Chapter 7, is
K =
1
2
m
e
v
2
=
(9.11
× 10
−31
kg)(3.0
× 10
7
m/s)
2
2(1.6
× 10
−19
J/eV)
= 2.6
× 10
3
eV .