10 September 2015
Lab Report
We looked at drops of oil through a small hole and got them still by using a high voltage.
After we put our eyes on a drop, we quickly lowered the voltage to zero. Then we used a digital
watch to see the time that the oil drop
X-Ray Spectra
We have seen that hydrogen emission lines come in groups, and that the shortest
wavelengths of light it can produce fall in the UV portion of the spectrum. Clearly, x-ray
wavelengths would have to come from other atoms. In fact, the Rydberg
Wavicles
It has previously been shown to follow directly from Maxwells equations that for an
electromagnetic wave of constant average intensity, the photonic pressure P in empty
space is given by P = P/Ac, where P is the power in the wave, A is the area,
Voltage (Electric Potential)
If the path by which charged particles follow an electric field does not matter, such as for
electrons in an electrical circuit, it would be more convenient to have a non-vector
quantity that essentially indicates how much pot
Using Relativity
Having been shown the odd equations that must be
employed when relativistic speeds are involved, it
is now time for you to see how to use them. One
useful device for glimpsing the peculiarities of
relativity is a modified form of a space-
The Uncertainty Principle
If the entire universe consists of waves when viewed on the smallest scales, what is a
particle? A particle is a wave packet. Consider the graph shown below where two sine
waves of slightly different frequency are superposed, cre
Transformers
A transformer is an electrical device
that takes advantage of inductance in
order to convert one voltage/current to
another voltage/current. The basic
I
construction is shown in the figure to
I
the right. Two coils of wire are wound
+
around
Radiation Toxicity
The image at right depicts a molecule of an extremely toxic substance. Since its
initial identification in 1917, it has been shown that a dose as little as 10 mg can
result in painful softening and swelling of the bones, yellowing and p
Thin Lenses
A lens wouldnt be much good if the
only function it had was to focus or
spread parallel rays coming from a
near-infinite distance. Fortunately,
lenses perform interesting operations
on rays under other conditions, too.
For instance, a convergi
Thin-Film Interference
When any wave encounters an interface between mediums, there is always a reflection
backward from the interface whether or not part of the wave continues into the new
medium. Consider a thin film of oil on the surface of a puddle of
Single-Aperture Interference
When coherent light shines through a single small slit onto a screen, the multiple slit
diffraction equation (2l s i n = N ) fails to predict the maxima and minima. The first
problem is that l was used to describe the distance
Simplifying Resistive and Capacitive Networks
Any network made purely of resistors or of capacitors can theoretically be simplified
down to a single equivalent value by replacing each valid series or parallel pair with the
appropriate equivalent. It is as
The Rydberg Equation
Using the quantum mechanical resonance model for the electron cloud in atoms, we can
understand the absorption or emission of photons as resulting from the electron cloud
expanding out to a larger shell or contracting inward to a smal
Resistors
A resistor is an electrical circuit element made out of a material that conducts electrical
current, but not as well as a metal wire. Electrical current (I) is the flow of electrical
charges, and in direct current (DC) circuits, is pictured as g
Resistive DC Circuits
Direct current (DC) means that the current flow in a circuit is steady
rather than varying in time. Batteries and plug-in chargers for various
devices are two examples of DC. The usual symbol for a battery is
shown at right, along wi
Special Relativity
We have seen that relativity requires a correction to the speed of an object as measured
from a different inertial framespecifically, this denominator: 1 vv/c. Notice,
however, that for small values of v or v, this corrective factor is
Relativistic Velocity
At the core of physics, at least in principle, is the notion of logical consistency: A fact
isnt a fact if it contradicts itself. If we can overcome our natural human resistance to
accepting counterintuitive realities, there is a gre
Refraction Effects
Suppose, for ease of calculation, that we have a sample of a material with an index of
refraction of exactly 2, and we are observing the effects of shining a laser out of the
material to the surrounding air (n = 1) at various angles. As
Rays and Reflection
A large number of electromagnetic waves all moving in
the same direction at the same time constitute what is
called a wave front. Since each wave within it consists of
a small bundle of wavelets that were emitted together as a
pulse, i
RC Circuits
A circuit consisting of one resistor and one capacitor can exhibit exponential behavior
due to the time it takes to charge the capacitor and to the resistors prevention of
unlimited current flow. The curves shown below are intended to remind y
(Quiz 01 was simply attendance on the first day.)
First find |E|=kQ/r. This requires finding r = (x + y) = (8 + 6) = 100 = 10.
So |E| = -kQ/100. (Note that Q has been replaced with -Q as specified.
Next, Ex = |E|(x/r) = (-kQ/100)(-8/10) = +8kQ/1000 = kQ/1
(Quiz 01 was simply attendance on the first day.)
First find |E|=kQ/r. This requires finding r = (x + y) = (8 + 6) = 100 = 10.
So |E| = -kQ/100. (Note that Q has been replaced with -Q as specified.
Next, Ex = |E|(x/r) = (-kQ/100)(-8/10) = +8kQ/1000 = kQ/1
Quantum Numbers
So far, we are aware of three integer quantum numbers for atoms: the principal (n > 0),
the angular (0 l < n), and the magnetic (-l m l ). It was subsequently shown that
there must be a fourth quantum number bearing a separate resonance of
Practice Test 1 Answers
1. (-36x -27y )N/C
2. 0 (Charge all migrates to the surface of metal.)
3. (9/0)r N/C
4. 5mN
5. 4F
6. 50mW
7. A,D,B,C or A,D,C,B
8. 4e -t/0.6s V
9. 290 A
10. (-500y -1000z )q0 N
Practice Exam 2
1. Light with a wavelength of 600nm passes through the double-slit
shown. If the distance to on the projection screen from the center to the
first-order maximum is 0.1m, how far is the screen from the double-slit?
60000nm
-50mC
2. Find the
Polarization
Although we know that the E-field, B-field, and
B
B
E
Poynting vector of an EM wave are all perpendicular
to each other, that does not mean that any two
E
parallel EM waves must have their electric fields
E
aligned in the same direction. The
The Photoelectric Effect
The exploration of interference phenomena had indicated that light existed as wavesin
contrast to gases, for example, which were clearly composed of discrete particles. Right
at the start of the twentieth century, however, experim
Physics 131 Practice Test 1
field
point
1. Find the electric field vector at the point shown.
Use k = 910.
3m
y
4m
x
-125nC
2. What is the electric field 10cm from the central axis of a long, uniform metal bar upon
which a total charge of 120C has been pl
The Nucleus
Ernest Rutherfords proposal that the atom consisted of negatively charged electrons
orbiting a positively charged nucleus triggered a great deal of curiosity about the
structure of that nucleus. It is important to understand how small it reall
Nuclear Physics
Alpha decay is essentially limited to the radioactive elements more massive than lead. It
is as though they are trying to lose as much mass as possible to move downward in
atomic number toward elements that have stable forms. We already kn