PHYS 135B Homework Set 11
Dr. Zo rba
Chap ter 27 :
1-) P4 9 Ho w m uch energy is needed to ionize a hydrogen at om in the
2=n
st a te ?
2-) P51 Determine the i onization energy of doubly ion ized li thium,
,Li2+
which h as
.3=Z
3-) P56 In the Sun, an ionized helium
)He(
+
atom makes a transition from the
6=n
state to the
2=n
state, emittin g a photon. Can t hat ph oton be absorbed by hydroge n atoms pr esent i n the
Sun? If so, between what energy states will the hydrogen atom jump?
4-) P60 An exc ited hydro gen atom c ould, in p rinciple, have a radius of 1.00 mm . What wou ld be
the va l u e o f n for a B ohr orbit of this si ze? What w ould it s ener gy be?
The rest is covered in C hapters 3 0 and 3 1:
5-) Estimate the diame ter of the following nuclei:
(a) 1
1H
(b) 20
40Ca
(c) 82
208 Pb
(d) 92
235 U
6-) Say, you want to break a n Alpha pa rticle int o its cons tituents ( protons, neutrons , electrons).
Given are: mass of Alpha particle = 4.0026u, mass of 2 protons = 2.0156u, mass of 2 neutrons =
2.0173u , where u is the atomic mas s unit = 1 .66x10-27 kg. Would this requi re energy, or would it
release energy? Show this by ca lculat ing the re action energy, Q.
7-) In f usion r eactio ns, usually two l ight nu clei combi ne to form one heavi er nuc leus. W hen one
measure s the sum of the masses of the two light nuc lei and th e resultin g heavier nucleus , one
sees that the latter is not matching exactly the former. In fact, the latter is a bit less massive
than th e sum o f the masses of the two lighte r nucle i. Why is this? W here did t he differe nce in
mass go?
8-) (a) What is fission?
(b) Wha t is fusio n?
9-) Calculate the binding energy an d the aver age bin ding energ y per nucl eon of
Also, , .
10-) Find t he reactio n energ y, Q, and ind icate the type fo r the followi ng nuclear reaction:
,
where the masses are as follows: