Electricity
-Moving charges through a wire.
positive charges (+) = protons
negative charges (-) = electrons
In order for something to be charged there must
be more of one charge than the other. For example, something that is positively
charged has more protons than electrons. Something that is negatively charged
has more electrons than protons. However, when there is an equal number of
protons and electrons it would become neutral.
It is important to remember that charges that
are alike will repel and charges that differ will attract.
There are three ways that something becomes
charged: induction, friction, and contact.
In friction, the electrons are stolen. Contact
transfers electrons. Induction charges without contact.
When you
take of a sweater, your hair stands up because of friction. The sweater
rubs up against the hair and steals electrons through friction. The sweater
then becomes negative and hair becomes positive.
We know that because like charges repel, the
positive hair strands repel each other and stand up.
Friction
also causes clothes to stick together in a drier. This is because the clothes
rub together, creating friction. Some clothes gain electrons becoming negative,
while others become positive. Since opposite charges attract, the clothes with
stick. This is where drier sheets become useful as they absorb electrons and
make the clothes positive and repel each other.
Induction
is what causes lightening. The clouds rub together and become charged through
friction. The ground becomes
positive through induction (a cloud is negative).
The cloud’s negative charges and ground’s positive charges leap towards each
other through the air and the pathway may become completed. If this happens, it
will release heat, light, and sound, creating lightening.
Because
lightening produces heat, it also causes fires. In order to prevent this,
lightening rods are placed on buildings as lightening is attracted to pointy
objects. If the lightening were to strike the rod, it would run the charges
along the building and into the ground. This keeps the building safe.
Polarization
is when the charges within an object separate, creating both positive and
negative sides.
For this reason, plastic wraps stick to ceramic
or glass bowls and not metal ones. When a plastic wrap is removed from the
container, it is charged by friction and becomes negative. When it is brought
near the bowl, the bowl’s protons attract and the negative charges move away.
Thus, it becomes polarized. The plastic wrap sticks because opposite charges
attract. We know this because of Coulomb’s law which states that the smaller
the distance, the greater the force, and the greater the distance, the smaller
the force.
We know this because F=kq1q2/d2
Electric Fields are areas of influence around a
charge.
It looks like this when drawn. The arrows represent the direction a positive charge will be forced. When you have an electrical charge of 0, the charge experiences no force. An electronic encased in metal is safe because of
electric shielding. When the electronic is inside the metal box, its electric
field is 0, feeling no force. Metal allows charges to spread out evenly, and
the charges in the box will pulled in one direction while having equal and
opposite forces pulling them in the other direction.
Capacitors
are two oppositely charged plates.
For
example, when you take a picture with a camera, two oppositely charged plates
that are not connected. When charges are added to the plates it increases the
force between them. This increases energy of the electric field. Energy rushes
between the plates and is released as light. The flash is brief because of the
time the process takes.
Electric Potential energy is the energy
in electric fields.
Voltage is the difference in electric
potential. Voltage=PE/q
Volts (V) are electric potential.
Current (I) (measured in Amps) is caused by voltage and is energy
carried through wires with charges. There are two types of currents: Alternating Currents (AC) and Direct currents (DC). In AC the electrons move back and forth (a dance move of sorts).DC moves in one direction.
Resistance (R) (measured in ohms Ω) is the ability for
current to flow through a wire. For example, a light bulb with a high
resistance is long, narrow, and hot. Low R is wide and short.
There are two types of circuits: Series and Parallel. Series normally has dimmer bulbs if one is added, low current, and a greater R. When one bulb goes out, the rest of the bulbs in series stop working. Fuses are wired in series. The fuse will burst if there is too much current flowing from the wall. The fuse prevents fires and keeps the house safe. Parallel has a lower resistance and a high current.The brightness remains the same if more bulbs are added. They all continue working if one burns out.
If you were figuring how much money it would cost to run a 40 watt light bulb connected to 160 Voltage source for an entire month and it costs .10 cents per KW hour, how much would it be?
there are 720 hours in a month
40 watts becomes 0.4 KW
(0.4)(720)= 288 KW Hours
288 * 0.10= $28.80
Ohm's law:
I=V/R
Meaning that current is directly proportional to voltage while being inversely proportional to Resistance.
Current is affected by both voltage and resistance.The less current there is, the more resistance it will have, and the more current, the less resistance. It can be altered by change in width, length, and temperature.
P=IV
Electric Potential= PE/q
When a light bulb burns out, the filament is cold with decreasing
resistance. Thus, the voltage and current increases. When a lot current flows
from the wall, it produces a lot of heat and causes the light bulb to burn out.
When you plug an American appliance to a European outlook, it is
very hazardous. American outlets are built with a lower resistance and lower
voltages. Where as European outlets have high voltage. When you plug in the
American device to the European, it is given more current than it is able to
process- causing fires.
Thanks for reading!
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