Download Project Summary - Berkeley Cosmology Group

Benjamin Ezeokoli
Moneel Chand
Miko Jones
Selina Villanueva
Summary of Electrostatics Project
Going into the project, we did not expect to go this in-depth into this project.
During our two weeks, our group engaged in the elaborate study of electrostatics (study
of electricity). We learned an enormous amount in this topic, much more than we thought
we would learn. The first week, we began by learning about Ohm’s Law which is V=IR
(i.e. Voltage=Current [Resistance]). We then continued into the topic of magnetic fields,
which we learned are created by flowing currents in electrical circuits. We also learned
the most open rule of electricity, Ohm’s Law, which describes how to calculate voltage,
current, and resistance (or sometimes impedance, where it gets more complicated) in an
electrical circuit. The equation for Ohm’s Law is:
V=I*R
Where V is voltage, I is current, and R is resistance.
In the first week, we learned about Ohm’s law, which states that voltage is equal
to the current in the circuit multiplied by the equivalent resistance; this is modeled in this
equation V= I*R. The current in a circuit is measured in amperes or amps, while the
resistance is measured in Ohms. Voltage is measured in volts of course. To complete a
circuit, you need a voltage source, such as a battery, and a path for it to travel which will
result in current. All objects give some type of resistance whether it is a tiny amount or
by a large amount. So in a basic circuit there is a battery or alternate form of voltage, a
path, such as wire, for current to flow through and there is also a little resistance which
may occur in multiple forms. A form of resistance is a light bulb or even the wire that the
current flows through; they can basically be anything that restricts the flow of electrons,
i.e. current. All of what has been stated above is only true when the voltage source pushes
out a constant voltage in the same direction. When the voltage source only pushes out a
constant voltage in a constant direction, it is known as direct current or DC. Ohm’s law
changes when you come up to a voltage source that changes the direction of its “push”
constantly. This is known as AC or alternating current. The equation changes to V (f) =I
(f)*Z (f). The function of “f’ on this case relates to the frequency of which the voltage
source changes its direction in a second; for example, the wall outlet changes direction 60
times in one second, so you would plug in 60 for f in V(f). The “I” still remains as the
current, but now it becomes dependent on what the frequency is. “R” changes to “Z” in
the AC case. “Z” is simply impedance, which means that it is anything that blocks the
flow of electrons. The only difference in this case is that the impedance is also dependent
on the frequency. By the end of the week, we were able to figure out the basics of
electrostatics. We learned about Ohm’s law and about the difference in Ohm’s law
between the AC case and the DC case. Kyle called the first week “Electrostatics in a
Nutshell” and that was what it basically was.
A transformer is a device that transfers electrical energy from one circuit to
another, through inductively coupled electrical conductors. When a current flows through
a circuit, it can create a magnetic field; afterwards, this magnetic field induces another
voltage in a different circuit. Since that second circuit now has a voltage source, it
contains energy, which means that the second circuit now can make current flow through,
allowing energy to be transferred from one circuit to another. Magnetic fields exert a
magnetic force on moving electrons that are surrounding the nearby transformer and
circuits, which has created these magnetic fields. Likewise, when you change a magnetic
field in any way, it induces an electrical field. This electrical field exerts a force on all
electrically charged objects within the vicinity of the field. Together, these fields become
one force, called an electromagnetic field. The sources of the field are stationary charges
(electric field) and moving currents/charges (magnetic field).
Now everyone needs power in order to operate correctly. The same is in
machines, too. Power, in defined in physics is the rate of energy flow. The equation to
find the power is current times voltage, or energy per unit of time (E/T). You need power
in order to make actions happen. If there was no power, then there will be no energy, and
therefore, would be no life! To make the Jacob’s ladder work, we need power, and also
most importantly, current and voltage. The Jacob’s ladder can give an output of 10,000
volts. But, in order to keep this amount of power and current going, we need power,
which is supplied by energy. In the Jacob’s ladder, the air between the two metal rods are
broken down, by a process of ionization. As this occurs, the air conducts the electricity
through, broken by the amount of current and power is running through it, and completes
the circuit. As this occurs, we are able to see sparks, because of how the electricity has to
jump from one rod to the other, and in very rapid speeds. On the other hand, we
experimented, and arrived at an incident where the two rods were connected by a thin
soldering wire, and no sparks were shown. We learned that the electricity just flowed
through the wire, while not at all showing any sparks. The current of the electricity was
also lowered during this test. But, this was all corrected, when we arrived at the solution
to cut the wire. After we cut the wire, we saw that the electricity began to melt the wire,
and soon the Jacob’s Ladder was fully operational once more. From this small
experiment, we learned that electricity needed a lot of current in order to ionize the air, as
well as power.
In conclusion, we have learned that the one of the most important a widely known
rules of electrostatics is Ohm’s Law (i.e. V= I *R). V, or voltage can be understood as the
“pushing”, I or current, is how much flow there is, and R or resistance, relates to
“pushing against the flow”, in a electrical current. These all apply to the DC case (Direct
Current) and the AC case (Alternating Current). However, in the AC case, you need to
add a frequency to each variable, i.e. V (f) =I (f) *Z (f). Frequency refers to the height of
the sin wave (associated with time), and “Z” is the resistance, but is now dependant on
the frequency.
A magnetic field is created by currents and these fields affect other currents.
Inductors have impedance due to magnetic fields. An inductor looks like a series of
intertwined coils. These inductors create magnetic fields. Power, written as a function is
P=I*V. For a transformer, power needed is equivalent to V(1)/V(2)=N(1)/N(2).
Overall, we learned a great deal about the topic of electrostatics, which is covered by one
of its main principles, Ohm’s Law, which is the “central dogma” of modern electrostatics.