What is Electricity: Definition and 999 Discussions
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others.
The presence of an electric charge, which can be either positive or negative, produces an electric field. The movement of electric charges is an electric current and produces a magnetic field.
When a charge is placed in a location with a non-zero electric field, a force will act on it. The magnitude of this force is given by Coulomb's law. If the charge moves, the electric field would be doing work on the electric charge. Thus we can speak of electric potential at a certain point in space, which is equal to the work done by an external agent in carrying a unit of positive charge from an arbitrarily chosen reference point to that point without any acceleration and is typically measured in volts.
Electricity is at the heart of many modern technologies, being used for:
Electric power where electric current is used to energise equipment;
Electronics which deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies.Electrical phenomena have been studied since antiquity, though progress in theoretical understanding remained slow until the seventeenth and eighteenth centuries. The theory of electromagnetism was developed in the 19th century, and by the end of that century electricity was being put to industrial and residential use by electrical engineers. The rapid expansion in electrical technology at this time transformed industry and society, becoming a driving force for the Second Industrial Revolution. Electricity's extraordinary versatility means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is now the backbone of modern industrial society.
Im doing a project on school. I want to re-use energy. I know that it will not run forever (but i hope it runs very long). So i wanted to ask if the image below is right and i could use it at school. If it shouldn´t work please say what i can make better. Thanks for your Help!
Here is my image...
Greetings !New to the forums.
Here expanding my concept of what AC Electricity is
My question (correct me if wrong)..
If AC power alternates between +,- at a rate of 60Hertz/second and negative is used as -earth- at the AC generator
If the hot wire touches the ground would happen? (I think...
Homework Statement
The electric field strength is 2.50×104 N/C inside a parallel-plate capacitor with a 1.20 mm spacing. An electron is released from rest at the negative plate. What is the electron's speed when it reaches the positive plate?
Homework Equations
F = eE = ma
vf2 = vi2 + 2ad...
In the charged rod experiment, why didn't my hand neutralize the charge formed in the rod, since my body is a conductor and it is connected to the Earth?
Homework Statement
Homework Equations
For R, current I=E/R and for X, I=E/X... both are separate cases.
The Attempt at a Solution
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Why does the balancing change?
The potential difference across each resistor is E Itself right?
I tried by assuming an arbitary internal resistance r...
I'm doing a quality of measurements coursework at the moment, the coursework was to find the efficiency of a kettle, and to do this, one of the factors that I needed to find was the voltage.
So in 300ml of water, the voltage was 240.5V
400ml - 244V
500ml - 243V
600ml - 245V
700ml - 241.4V...
Homework Statement
Consider an infinitely long solid cylinder of uniform linear charge density λ1 and radius a inside a hollow cylindrical pipe of inner radius b and outer radius c and uniform linear charge density λ2. A cross-sectional view of the system is shown below(linked and attached)...
I need help. I am installing new networked alarm panels throughout a building. There is a room where one panel is and that panel is continually having components fail. While in this room it is also very common for me to receive a static shock when coming in contact with any metal. I realize...
People say that the voltage across one resistor is equal to the voltage supplied.
I've drawn a picture of a simple circuit with two points near the positive terminal. Apparently, if we take the potential difference of these two points, it will equal 9V according to the above saying (which can...
This is a concept that has long since plagued me. I will quote an article off of Google about the concept I am confused about:
"Consider a collection of static point charges located at position vectors (where runs from 1 to ). What is the electrostatic energy stored in such a collection...
So I'm having trouble visualizing how voltage drops more within different parts of a circuit, such as a resistor vs. wire. I know all the general equations but the concept is hard for me to comprehend and I am stuck on one notion. So, say you have a simple DC circuit with just a resistor and...
So I am trying to understand how a ULTC operates in the Reactive Power Control mode (it adjusts taps to control the reactive power in a line). What equation is governing it's operation, and what variables does it adjust in order to increase/decrease reactive flow?
Is it just the simple reactive...
So basically, I am inferring the following based off of what I've learned.
When we hook a battery up to a circuit, this creates a potential difference. Say we use a 9V battery. Here is a picture:
From what I know, the horizontal is a equipotential surface, and the vertical has different...
HI everyone. I'm an engineering strudent, looking for online material with exercises on diodes...anyone can send me a link here with explanations of the various exercises? Thank you very much :)
(1) I previously learned that a constant magnetic field causes a force on any electrons within its range. Clearly, this force would cause electrons to move. Isn't this creating a current?
(2) However, now apparently I am told that the only varying magnetic fields can create a current. I.e...
How exactly do the electrons move from the capacitor to the rest of the circuit? Do they fly between the capacitors plates, or can they only travel where there is a wire connection? (I.e., if a small chunk of our circuit looks like this: A-------| |-------B can an electron start from A, go to...
Suppose we have a circuit with two capacitors connected to each other, C1 and C2.
C1 is charged and has a potential difference of 5 V (V1=5V), but C2 is not charged (V2=0)
Apparently it is known that the potential difference of these two capacitors will want to reach equilibrium. So V1=V2...
Homework Statement
What amount of heat will be generated in a coil of resistance R due to a charge q passing through it if the current in the coil decreases down to zero uniformly during a time interval ##\Delta t##
Homework Equations
##dH=i^2Rdt##
##i=\frac{dq}{dt}##
The Attempt at a...
Hello,
Does anyone shield themselves from computer / monitor from EMF radiation? if so what materials do you use to cover/coat your electronics?
I am buying an EMF meter soon (Trifield 100XE) and plan on solving all my EMF issues, specifically around my computer tower, monitor, and other...
Homework Statement
A point charge q =+6.4 \mu \mathrm{C} is placed at each corner of an equilateral triangle with sides 0.29 \mathrm{m} in length.
What is the magnitude of the electric field at the midpoint of any of the three sides of the triangle?
Hint: if you are careful to examine the...
Homework Statement
Homework Equations
P = V^2 / R
1/Rt = sum(1/Ri) (parallel)
The Attempt at a Solution
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Since all the answer choices express the solution in terms of V^2 / R, I tried to find the voltage drop across resistor #2 to find the power. I collapsed the two parallel...
Homework Statement
If Q1 in the above figure is twice Q2 and both are positive, where can a point of zero potential be found?Homework Equations
V = kq/r
The Attempt at a Solution
I know that eventually I'll have to set it up so that kq/r = kq/r, but my problem is, how do you know where this...
Homework Statement
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In the above figure, if Q1 and Q2 are positive, where could a negative charge be placed and have a vertically upward net force on it?
Homework Equations
F = k|q||q| / (r^2)
The Attempt at a Solution
I wrote the force equations for the negative charge and both positive...
Homework Statement
Ignore the internal resistance of the battery and assume it is merely a battery. Calculate the equivalent resistance of the circuit.
Homework Equations
1/Req = 1/R + 1/R ... (parallel)
Req = R + R ... (series)
The Attempt at a Solution
I know this is fairly simple but I...
Homework Statement
The figure gives the electric potential V(x) along a copper wire carrying uniform current, from a point of higher potential Vs = 9.00 μV at x = 0 to a point of zero potential at xs = 3.20 m. The wire has a radius of 1.50 mm, and copper has a resistivity of 1.69 × 10-8 Ω·m...
Homework Statement
Capacitor 3 in Figure (a) is a variable capacitor (its capacitance C3 can be varied). Figure (b) gives the electric potential V1 across capacitor 1 versus C3. The horizontal scale is set by C3s = 20 μF. Electric potential V1 approaches an asymptote of 10 V as C3 approaches...
Homework Statement
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Consider the circuit above. You are given the following measured values:
V = 1.5 V
R1 = 100
R2 = 100
R3 = 50
R4 = 50
R5 = 50
Homework Equations
Kirchhoff's Loop Rule and Junction Rule
The Attempt at a Solution
I tried setting this up using the junction and loop...
I have several questions about poles and towers.
a. Does all of transmission towers carries three-phase powers? Is there no transmission towers designated for single-phase?
b. Does all towers are for transmission purposes only? Is there any towers in the world used for distribution instead of...
In my textbook it says that work done by a nonconservative force (an applied force) has the same sign as the change of potential energy?
For instance, if I push a positive test charge from an infinite distance away to a negative charge, then the test charge goes from high potential energy to...
Hi everyone.
On these days, by watching solar panels and similar stuff, I just thought about it, and why they take such a wide surface to produce energy, and why their output is often low, as we all know.
By navigating here on the internet, I've just seen a device called OPO (Optical...
A small thermocouple would produce tiny amounts of electricity as temperature unevenly fluctuates. But if I tried to store that energy using a diode and capacitor, I would guess that the tiny reverse current flow through the diode would be enough to not allow for such a self charging system to...
Hello, I want to create a motion using electricity, using the cheapest means possible (DIY). Basically I'm trying to rotate an object 90degrees when the current is on, and back to its original position when the current is off.
The questions are:
1) Is this possible?
2) Can this be done using...
Electrons are moving in moves in all sorts of directions, causing the net electric charge to cancel out. But, when you apply a voltage, there's a small amount of electrons that will move towards the direction in the direction of the voltage. This is called the drift speed. Am I right? I read...
In the direct current circuit, when you have a switch and you turn it on, you get the coil to generate a current to the opposite direction but the magnitude isn't big enough to offset the main one. But in the case of alternating currents, the coil seems to generate enough current up to the...
Hi everyone,
I just came across an exercise that asks me to explain how I would measure the change of resistance of a metal wire between a temperature of 0º C and 100º C. The answer to the question is below, what I don't understand is why is there a need to put ice in the water bath and the need...
Pardon me if I stated the title incorrectly/ informally. I just want to say about the title is about the 220 V, 60 Hz source (present in our outlets also) in our house by which comes from nearby electrical post.
I have four questions in this post/thread so kindly tell me if I need to edit this...
I currently get my electricity from an electric company. I would like to get a windmill installed on my roof to supplement my electricity needs. I want to be able to use the windmill to get as much free electricity as I can, and I would like to continue to keep getting the rest of the...
Is there any usage for a measuring microscope in an electricity laboratory as a part of any experiment?
We have a Mitutoyo measuring microscope in our fundamental electricity physics lab which is a course for sophomores.
We used it for apparent depth in our optics lab which is retired now!
I'm...
Say you have salt water. If you apply an voltage between two electrodes Na+ ions will drift towards the negative electrode and Cl- ions towards the positive electrode. If a redox reaction happens at the electrodes, the ions transfer electrons to the electrodes and current continues to flow until...
Hello everyone...
Help me out..
I installed a geyser 3 weeks back which has a rating of 15A and I connected it to a 32A MCB. This is connected to a 16A separate MCB in the main board. Whenever I turn on the geyser, it works for some 10mins and then turns off without water getting heated. I...
Homework Statement
Copy the diagrams in Figure 7 into your notebook, and draw the direction of the conventional current or the
magnetic field lines. Also indicate the location of the north and south poles where appropriate.
FIGURE 1
FIGURE 2
Homework EquationsThe Attempt at a Solution
Using...
I'm working an electricity broking desk at a finance firm this summer, and was hoping someone could clarify the science of it all for me.
-For example, a plant has 350MW of capacity. Say 350MWh are demanded for a one hour period. Assuming this plant bids successfully to supply the full amount...
Hi guys,
Basically I'm studying electricity at high school level and I need recommendation on a decent book that covers the basics on electricity as the official textbook misses a lot of detail and there's limited practice questions. I've been to several libraries but the books I've found, most...
Homework Statement
After a capacitor of capacitance ##C_1## is charged up to a voltage ##V_o##, the Battery is removed from the circuit. Another capacitor of capacitance ##C_2## is connected in series with the capaciotr ##C_1##. Find the charge on each capacitor after equilibrium is attained...
Homework Statement
I got questions a) and b), but I'm stuck at c) and d).
Homework Equations
Kirchhoff's Loop and Junction rules.
Equivalent resistance in series: Req = R1 + R2
Equivalent resistance in parallel: Req = ((R1)-1 + (R2)-1)-1
The Attempt at a Solution
I really haven't gotten...
Gauss's Law states that if a Gaussian Surface encloses a charge ##q_{enc}## then the electric flux through the Gaussian Surface is given by ##\phi=q_{enc}/\varepsilon_{o}## .
It also states that any external field does not contribute to the Electric Flux through the Gaussian Surface.
I am bit...
Hey there...
As far as I know, electric flux is a scalar quantity which means that negative values are smaller than zero. This concept really confuses me since most of the exercises I dealt with suggest that negative flux somehow is larger than zero flux
Example 1
the uniform field is directed...