Tube Closed at One End
Resonance in an Air
Column Closed at One End
The closed end must be a node
The open end is an antinode
fn = n
Speed of Sound in Air
m
T

v =  331 
s  273 K

331 m/s is the speed of sound at
0° C
T is the absolute temperature
Quick Quiz #00
In the speed of light lab, what was the
actual wavelength of the microwaves?
Note: f = 2450 MHz
A.12 cm
B.6 cm
C.7 cm
D.9 cm
E.8 cm
v
= n ƒ1
4L
n = 1, 3, 5, K
There are no even multiples of the
fundamental harmonic
Quick Quiz #000
In the speed of sound lab, what was in
resonance?
A.Water and air
B.Sound waves going in 1 direction
C.Tuning fork and air in room
D.Tuning fork and air in column
Quick Quiz #0
In the speed of light lab, the distance
between melted marshmellows was equal
to:
A.λ of the EM wave
B.λ/2 of the EM wave
C.3λ/4 of the EM wave
D.λ/4 of the EM wave
Exam Quiz #1
Exam Quiz #2
The energy of a photon with wavelength = 300 nm is:
a.1.6 x 10 -19 Joules
b.6.6 x 10 -19 Joules
c.1.6 x 10 -34 Joules
d.6.6 x 10 -34 Joules
In the photo-electric effect:
A.Light of any wavelength may produce an electron
if the light beam is intense enough
B. The wavelength of the light must be short enough
to over come the metal’s work function to produce
an electron
C.The wavelength of the light must be long enough
to over come the metal’s work function to produce
an electron
Exam Quiz #3
Exam Quiz #4
A. H. Compton’s middle name is:
The important feature of the Compton Effect is that:
A.Homer
B. Harold
C.Holly
D.Herman
E.Henry
A.Photons collide with electrons like billiard balls
B. Photons have momentum
C.Momentum and energy are conserved
D.The incoming and outgoing photon have different
wave lengths
E. All of the above
Exam Quiz #5
What is the momentum of an electron with a
DeBroglie wavelength of 0.33 nm?
A.2 x 10 -24 kg-m/s
B.3 x 10 -24 kg-m/s
C.2 x 10 -34 kg-m/s
D.3 x 10 -34 kg-m/s
E.6.6 x 10 -34 kg-m/s
λ=
h
h
=
p mv
Exam Quiz #6:The Uncertainty
Principle may be expressed as:
h
∆x∆px ≥
4π
h
∆x∆py ≥
4π
h
∆E∆t ≥
4π
∆E
h
≥
∆t 4π
A.
B.
C.
D.
E. Both A. and C.
The Electromagnetic Spectrum
Shortestwavelengths
wavelengths
Shortest
(Mostenergetic
energeticphotons)
photons)
(Most
Quick Quiz
Which of the following is true?
A.c=λ/f
B.c= f/λ
C.c= λf
D.f=c λ
E.c λ =f
= hf
hf =
= hc/λ
hc/λ
EE =
λλ
h = 6.6x10-34 [J*sec]
(Planck’s constant)
Longestwavelengths
wavelengths
Longest
(Leastenergetic
energeticphotons)
photons)
(Least
Electromagnetic Waves- Transverse Waves
r
r
The E and B fields
are perpendicular
to each other
Both fields are
perpendicular to
the direction of
motion
Therefore,
em waves are
transverse
waves
Quick Quiz
Electromagnetic waves are
A.Not found in regular life
B.Composed of E and B fields
C.Composed of corpuscles
D.Can be made up of either E
or B fields
E.Can not be seen by the
human eye
Electric Charges in Magnetic Fields
This force has a maximum value when
the charge moves perpendicularly to the
magnetic field lines
This force is zero when the charge moves
along the field lines
This force is zero if the charge is stationary
F = Bqv sin θ
Right Hand Rule #1
Moving charges feel magnetic force
perpendicular to path of motion
Superconducting magnets
300000 Gauss or 30 Tesla
Earth’s magnetic field
-5 T
0.5 G or 5 x 10
Quick Quiz
How many G in a T?
D. 105
A.10-5
E. 0.5 x 10-5
B.10-4
C.104
Place your fingers
in the
r
direction of v
Curl the fingers in the
direction of the r
magnetic field, B
Your thumb points in
the direction
of the
r
force, F , on a positive
charge
If the charge is negative,
the force is opposite that
determined by the right
hand rule
Direction of B Field produced by a
Long Straight Current carrying Wire
Magnetic Field of a Current Loop
Current in wire is moving charge
Produces Magnetic Field
Right Hand Rule #2
Grasp the wire in your
right hand
Point your thumb in the
direction of the current
Your fingers will curl in the
direction of the field
The strength of a
magnetic field
produced by a wire
can be enhanced by
forming the wire into
a loop
All the segments,
∆x, contribute to the
field, increasing its
strength
Lenz’ Law – Case #2
Moving Magnet Example
Magnetic Flux
The emf is actually induced by a change in the
quantity called the magnetic flux rather than
simply by a change in the magnetic field
Magnetic flux is proportional to both the
strength of the magnetic field passing through
the plane of a loop of wire and the area of the
loop
Lenz’ Law
The current caused by the induced emf
travels in the direction that creates a
magnetic field with flux opposing the change
in the original flux through the circuit
Induced Field
A bar magnet is moved to the right toward a stationary
loop of wire
As the magnet moves, the magnetic flux increases with time
The induced current produces a flux to the left, so the current is
in the direction shown
Quick Quiz: In what direction would the induced flux point if
the bar magnet were moved AWAY from the ring?
A. LEFT B. RIGHT
The Electric Vector in Light Waves
Polarization of Light Waves
Polarization by Reflection
When an unpolarized light beam is reflected
from a surface, the reflected light is
Each atom produces a
wave with its own
r
orientation of E
All directions of the
electric field vector are
equally possible and
lie in a plane
perpendicular to the
direction of
propagation
This is an unpolarized wave
It depends on the angle of incidence
Completely polarized
Partially polarized
Unpolarized
If the angle is 0° or 90°, the reflected beam is
unpolarized
For angles between this, there is some degree of
polarization
For one particular angle, the beam is completely polarized
The angle of incidence for which the reflected beam is
completely polarized is called the polarizing angle θp
θp is called Brewster’s Angle
n=
sinθ p
cos θ p
= tanθ p