Position:

1
Position (your seat ).. Your
Name Last, First Name of
Workshop Instructor Last, First.. Exam
(3) Date April 19th,
2005
1
2
3
5
6
7
9
4
10
11
12
13
14
15
Use the following constants, if necessary 1
eV1.6?10-19 J me9.1?10-31 Kg
E1-13.6 eV c3?108 m/s h6.62?10-34
Js r10.529?10-10 m 1 nm10-9 m
R1.097?107 m-1
Q1 (3 points). An ordinary incandescent lightbulb
emits A. Polarized light B. Partially
polarized light C. Unpolarized light D.
Polarized and unpolarized light Please choose
the correct answer and explain it briefly.
2

• Q2 (3 points). What is the photoelectric effect?
• The phenomenon that when light shines on a metal
  surface, photons are emitted
• The phenomenon that when light shines on a metal
  surface, nuclei are emitted
• C. The phenomenon that when light shines on a
  metal surface, electrons are emitted
• Please choose the correct answer and explain it
  briefly.

Q3 (4 points). The photon energy is proportional
to its A. Frequency B. Wavelength C.
Period Please choose the correct answer and
explain it briefly.
3

• Q4 (10 points). A light ray is incident on a
  potassium surface.
• The work function W0 for potassium is 2 eV.
• If the light is red, with a wavelength of 700 nm,
  are any
• electrons emitted? If so, what is their maximum
  kinetic energy?
• What is their maximum speed?
• B. The same as part A, but replace the red light
  by green light
• with a wavelength of 540 nm.
• C. The same as part A, but replace the red light
  by blue light
• with a wavelength of 400 nm.

4
Q5 (7 points). What is the energy in eV of an UV
photon of wavelength ? 300 nm? A. 4.110-2
eV B. 4.1 eV C. 41 eV D. 410 eV
Q6 (10 points). An X-ray flux consists of photons
with a wavelength of 0.3 nm. How many of the
X-ray photons must strike a surface in one second
to deliver a power of 110-12 W? A. 1 B.
1524 C. 20000 D. 4108 Reminder Power is
Energy divided by Time.
5
Q7 (3 points). What is the wavelength ?, of an
electron traveling at 2 x 106 m/s? A. 2?10-5
m B. 3.6?10-8 m C. 3.6?10-10 m D. 2?10-25
m
Q8 (12 points). What is the maximum energy for an
electron bound to the nucleus in the Bohr model?
A. infinity B. infinity C. -13.6 eV D. 0
6
Q9 (9 points). How much energy in Joules does it
take to excite a hydrogen atom into its first
excited state? The energy corresponding to the
ground state is -13.6 eV. A. 10.2 J B.
1.6?10-19 J C. 1.63?10-18 J D. 3.4 eV
Q10 (12 points). What state (n ?) would the
Bohr atom be in to have a diameter of 1 mm? A.
124 B. 2700 C. 3074 D. 4348
7
Q11 (10 points). What is the shortest wavelength
in the Balmer series? For the Balmer series, the
lines are transitions from the level n2 to the
next excited states, namely n3, 4, 5, 6. A.
0.15?10-6 m B. 0.36?10-6 m C. 0.45?10-6 m D.
0.66?10-6 m
Q12 (7 points). Which line in the figure
represents the binding energy? Here, r is the
separation between nuclei and the vertical axis
is the atom-atom potential energy A) D B)
E C) F
8
Q 13 (7 points). Which line in the above figure
represents a region of attraction? A) A B)
B C) C
Q 14 (5 points). What is the difference between a
covalent bond and an ionic bond?
Q 15 (5 points). Which of the following is a very
weak bond? A. Covalent B. Ionic C.
Hydrogen D. van der Waals Please explain your
answer.