Problem 20.6
Two identical metal spheres A and B are connected by a metal rod. Both are initially neutral. 1.01012
electrons are added to sphere A, then the connecting rod is removed.
Part A
Afterward, what is the charge of A?
Express your answer using tw
Derivation of Gauss's law
Gauss's law is another form of Coulomb's law that allows one to calculate the
electric field of several simple configurations. Gauss's law relates the electric field
lines that "leave" the a surface that surrounds a charge Q to t
Examples for electric field and equipotential lines
Example #1
Problem:
Is the electric field zero at a,b,c,d?
yes,no,no,no
Is the electric potential zero at a,b,c,d?
yes,yes,yes,no
Example #2
Problem:
What is the magnitude
and direction of the
electric f
Examples for Gauss's law
Example #1
Problem:
Consider a sphere of radius R=8.0m with a charge Q=3.0mC uniformly
distributed throughout the volume. What is the electric field at a distance r=4.0m?
Solution:
If one draws a Gaussian surface with radius r, th
Electrostatics Lab Report
Analysis of Results
1. In our lab, we realized that the electrostatic force is strongest with the fleece. The balloon
seemed to pick up a charge when rubbed with the fleece. In general objects pick up charge with
dry items. Water
Electrical Energy
1.) In this experiment we used a small motor to lift different amounts of mass. While the motor lifts,
we measured the current through and the voltage across. We used these quantities to get the
Power. Power is measured in SI unit of Wat
Waves
1. There are a few different types of waves studied: Longitudinal, transverse, and reflection. A
longitudinal wave travels like a slinky. A transverse wave travels through something like air. A
reflective wave travels through something like a rope a
Lab 9; Resonant Air Columns
1. Sound waves can constructively build on each other. In this experiment we measured
the wavelength given the frequency with a known length of pipe. We could adjust the
length of pipe accordingly until the loudest noise was he
Capacitors
1.) In this lab we set up circuits to understand how capacitors work, and prove that Q=CV. We set
up different circuits including series and parallel. We had to use the equation Ceq= C1+C2. to
check series, and 1/Ceq= (1/C1+1/C2) to check paral
Resistor and Resistivity
1. In class we made resistors out of playdough. We made different shapes and used the resistivity
of the material and Ohms law to determine the resistance. We had to measure out the
diameter, and length of the cylinder playdough w
Earths Magnetic Field
1.) In this experiment we will determine the strength of the Earths magnetic field by
running a current thru a coil and a magnetic field will be produced perpendicular to the
coil, at the angle . We first will observe with a dip need
Lab 6: Magnetic Field in a Coil
1.) During this experiment we will use a frame to wrap wire around and pass current
through it. By passing current through the wire we should be able to obtain a magnetic
field reading using a magnetic field sensor and Logg
The Double Slit
1. The theory we used in this lab is known as two-slit interference patterns to
calculate the wavelength. When light is passed through the two-slit
experiment set up it is noticed that the light interferes constructively. This
constructive
Adding velocities
Consider two objects. The first object moves with velocity v relative to the
second object, while the second object moves with velocity u with respect
to an observer. In Newtonian physics the observer would say that the
velocity of the f
Example #1
Problem:
a.) An image is located at exactly the same position as an object for a mirror of
focal length 6 cm. What is the object distance?
Solution:
Use the formula
with di and equal to get
do = 12 cm
b.) If the height of the object is 4.5 mm,
Problem 21.14
Part A
What is the electric potential at points A, B, and C in the figure?
Enter your answers numerically separated by commas. Express your
answer using two significant figures.
ANSWER:
VA,VB,VC
V
=
Part B
What is the potential energy of an
Focal points of curved mirrors
Mirrors can focus light. Focusing light is necessary for making images
with film or recorders. Of course, lenses are more common, but mirrors
are also used, e.g. the Hubble space telescope. To understand focusing,
we first c
Length contraction
Moving objects appear shorter in the dimension parallel to their velocity, again by
the g factor introduced previously. To derive the contraction we again consider a
light clock as the case of time dilation, only in this case we conside
Real images
On the previous page, we assumed that the light rays approaching the
mirror were all parallel. This is true for a distant object, but not true for
an object a finite distance removed from the mirror. We now derive the
point at which the light
Virtual images
For an object far away from a concave lens, an image appears at the
focal length. As the image is moved closer, the image appears further
away. However, when the object reaches the focal length the image moves
to infinity, and disappears al
Equipotential lines
Equipotential lines provide a quantitative way of viewing the electric potential in
two dimensions. Every point on a given line is at the same potential. Such maps
can be thought as topographic maps.
For instance consider the map of th
Charge near conductors
Here, we consider what happens when charges are near conductors. For
instance consider a spherical neutral conducting shell with a point charge Q
placed in the center.
The field inside the shell must be the same as for a free charge
Definitions of electric fields and potentials
From Physics 231, and from the previous lecture one should be comfortable with
the concepts of force and potential energy. From Physics 231, one used the
equation:
where
is the potential energy added to an obj
Examples for relativity
Example #1
Problem:
A muon has a lifetime of 2.2E-8 s in its own rest frame. If it travels with a speed
of 0.95c, how far will it travel before it decays?
Solution:
The distance if vt, but the time is longer by a factor .
20.1 m
Ex
Michelson interferometer
The Michelson interferometer was the crucial instrument for proving the nonexistence of the ether. The interferometer produced an interference pattern from
light being spit into two separate paths then brought together again as sh
Fundamental postulate of relativity
Relativity has a lot of surprising consequences: Moving clocks run slow and
moving meter sticks are short. This bizarre behavior all follows from two
fundamental postulates. The first postulate is implicit in Newtonian
Units for electric potential and fields
Previously, we noted that electric forces are in Newtons ( N), electric potential
energies are in Joules (J), and charge is measured in Coulombs (C). Since
electric fields and potentials are obtained by dividing the
Electric Field Mapping
1. In the lab we found voltage points to trace equipotential surfaces and map electric fields
produced by a potential difference. The theory behind this was that equipotential lines do not
intersect with one another, they do interse