32.

(a) The rest energy of an electron is given by E = m

e

c

2

. Thus the momentum of the photon in question

is given by

p

=

E

c

=

m

e

c

2

c

= m

e

c

=

(9.11

× 10

−31

kg)(2.998

× 10

8

m/s)

=

2.73

× 10

−22

kg

·m/s .

We may also express the momentum in terms of MeV/c: p = m

e

c

2

/c = 0.511 MeV/c.

(b) From Eq. 39-7,

λ =

h

p

=

6.63

× 10

−34

J

·s

2.73

× 10

−22

kg

·m/s

= 2.43

× 10

−12

m = 2.43 pm .

(c) Using Eq. 39-1,

f =

c

λ

=

2.998

× 10

8

m/s

2.43

× 10

−12

m

= 1.24

× 10

20

Hz .