The study of the presence and flow of electric charge. Charges, currents, fields, potentials.
0
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0answers
38 views
Experimental study of the Photoelectric effect [duplicate]
As I was reading about the experimental arrangement for photoelectric effect, I saw a diagram that puzzled my knowledge of electrodes. I found that in the experimental setup the cathode of the ...
0
votes
1answer
24 views
Electricity directly from heating a material [duplicate]
I am looking for some more information about how to obtain electricity from heat directly. This e.g. involves the Seebeck effect, as I have found it is called, where a material produces a voltage ...
-2
votes
2answers
56 views
Is it possible to generate electricity using a water tower?
Is it possible to build a water tower that will provide enough pressure to run an electricity generator? A water pump can be used to send water up to the tower. The water pump can be powered by solar ...
-1
votes
1answer
20 views
heat energy and resistance of an elctric circuit
Very often it is said that "heat is developed" in a resistance when there is an electric current in it. But as far as I know heat is defined as a form of energy being transferred due to difference in ...
3
votes
2answers
93 views
Why two connected 1.5 volt battery become 3 volt
Why two connected 1.5 volt battery become 3 volt?
If one battery plus side is connect to minus side of another battery, there should be a current flow between them until no free charge move anymore, ...
1
vote
0answers
27 views
How to size an electromagnet
How can I size an electromagnet? For example if I would to attract a mass of $x$ kg what are the calculations that I must do to size the ferromagnetic core and of course the solenoid? And thus, how ...
1
vote
1answer
32 views
Why does a moving electric charge have nonuniform electric field lines?
The electric field of a stationary electron is uniform, radially symmetric with straight field lines. However, the electric field of a moving electron still has radial and straight field lines, but ...
1
vote
0answers
69 views
How does current flow in a irregularly shaped heterogeneous resistor?
The motivation for my question is understanding how electricity gets through your skin as opposed to running along it, and how the presence of things like water on the skin affect the relative ...
11
votes
5answers
195 views
Why are wires in simple circuits approximated as equipotentials?
I just answered this question:
Voltage in a circuit
by asserting that any two points joined only by a wire, but no other circuit elements, are at the same value of the electric potential. It is, of ...
4
votes
2answers
76 views
Voltage in a circuit
Suppose I have a following circuit:
I do not understand, why the potential difference between the points $c$ and $d$ is equal to the potential difference between the points $b$ and $a$? That is, ...
0
votes
0answers
25 views
Electrical properties of molten gallium arsenide
I'm looking for the resistivity and magnetic permeability of molten gallium arsenide, but can only seem to find the values for the solid material at room temperature (e.g., Wikpedia). Not even ...
-4
votes
1answer
32 views
Relation between resistance and electric field permeability [closed]
What is difference between resistance and electric field permeability.
can u give me a relation between resistance and electric field permeability?
please explain me in a simpler manner.
7
votes
2answers
143 views
What could magnetic monopoles do that electrically charged particles can't?
I understand the significance to physics, but what can a magnetic monopole be used for assuming we could free them from spin ice and put them to work? What would be a magnetic version of electricity?
...
2
votes
1answer
43 views
How are excess charges distributed over non-spherical conductors?
My textbook gives the following explanation on how excess charges are spread over conductors:
The excess charge on an isolated conductor moves entirely to the
conductor's surface. However, ...
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votes
1answer
30 views
Would the empirical behavior of a simple circuit match my model of it?
I have a practical problem in E&M which has baffled me and and my electrician. The copper water pipes in my house are carrying a current of small potential (~1V) AC current. Here is my ...
0
votes
0answers
29 views
About electric current analogy
my teacher gave me this analogy to the electric current , the wire is like a pearl necklace where the pearls can move, the current or the movement of electrons is like putting your fingers between 2 ...
-10
votes
1answer
42 views
Chapter 35-Electricity and Magnetism [closed]
A light bulb connected to a 3.0-V battery draws 1.2 A of current. Calculate the resistance of the bulb.
0
votes
1answer
41 views
Total current of two sources in series? [closed]
Here is a question that a friend asked me. He had to an experiment in school and do some calculations afterwards. Those calculations require maximal current that the DC source can produce. He has ...
4
votes
1answer
138 views
Does rubber insulate lightning more effectively than air?
Last week, an Ars Technica writer was struck by lightning. He says that the 911 operators were concerned about whether or not he was wearing shoes at the time, but he didn't think it would make much ...
1
vote
1answer
42 views
Power in hydraulic analogy
In hydraulic analogy one compares electrical circuits with water circuits. For the electric case the formula $P = U \cdot I$ for the electric power holds. The analogous formula for water flow would ...
-5
votes
2answers
50 views
Street Light Interference Phenomenon [closed]
Is there a scientific approach that can explain the street light interference phenomenon? Everytime I walk past a Streetlight it turns off.
0
votes
0answers
19 views
Faraday Effect, Satellites, and Electromagnetic Atmosphere [duplicate]
If I launched a Satellite into orbit and dropped a silver wire caged in carbon fiber with aerodynamic wings (for support), would the faraday effect of the wire traveling through earth's ...
-2
votes
0answers
49 views
electrostatic repulsion that is troubling me [closed]
Consider a homogeneous ring of radius $R$ made of a thin wire of cross section $A (R^2\gg A)$. A Charge $Q_1=10\mu \mathrm{C}$, uniformly distributed over the ring, broke it apart due to electrostatic ...
0
votes
1answer
21 views
Lightning and Charge Displacement
There is something I don't really understand about flashes of lightning.
When a flash occurs, how come electricity be transferred at the speed of light since electricity's displacement is very slow ?
...
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votes
1answer
42 views
Current in AC circuit
The problem is to find the current on the capacitor. $I''$ should be correct, but I don't know how to construct the formula for $I'$.
I managed to get the value for $I_c$ using Thevenin and Norton ...
0
votes
2answers
79 views
What happens when non-equal voltages are put in parallel? [duplicate]
If two batteries, say 2 volts and 5 volts, are connected in parallel, are there any problems? The higher voltage will then want to flow out, but also towards the lower 2 volt battery end, right?
-2
votes
0answers
34 views
Increasing Amps [closed]
I am not sure if this is the place to post this, but both physists and electricians should be able to help here, so I am going to cross post with DIY (sorry if this really annoys people - I know it ...
1
vote
1answer
32 views
Why should a battery not give current in order to measure EMF?
Emf is the "potential difference (PD) across the terminals of a battery when it is giving no current to the circuit."
What does "when it is giving no current mean"? Will the PD across the terminals ...
-2
votes
0answers
30 views
Circuits using generators and cells and capacitors [closed]
This question was in a science worksheet we had, the description read as follows:
Tim has designed a generator that uses wind power and provides 9V. He decides to design a circuit using diodes ...
-2
votes
1answer
42 views
Resistance of a copper wire [closed]
Resistance of a copper wire is 20ohm. If the diameter of the wire is 5mm and length 1ohm. Find the resistivity of the copper.
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votes
0answers
13 views
Software for electric schemes [migrated]
I am looking for an open source software for creating electric schemes. Could you, please, recommend your favorite programs? Also, it will be better if your programm can do other schemes (for ...
3
votes
1answer
118 views
Can Earth's Magnetic Field Create Electricity?
If the earth has a magnetic field, can it, in theory, be run through a conductive metal coil to create electricity?
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votes
1answer
34 views
The nature of resistance at copper wire terminations
Speaker wire consists of twisted copper strands, around AWG 22 thru 10. As good consumers know, one must consider resistance when wiring speakers. How do the wire terminations contribute to the ...
1
vote
0answers
38 views
Contact electricity and photoelectric effect
Most universities provide an experiment about the photoelectric effect to determine $h$ by measuring the stop voltage against the light frequency and calculating the slope $h/e$.
But mostly they also ...
1
vote
2answers
135 views
What is a “gravitational cell”?
I am not a physicist, and I don't understand the details of electromagnetism. Anyhow, I was looking for how the batteries work in Google. So, I came across this article: "How batteries work: A ...
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votes
1answer
60 views
Volts, Amps, and Practical Electrical Knowledge [duplicate]
I've heard people say that high amperage or high voltage is dangerous to humans-aren't they both? And what are the advantages to high amperage versus high voltage? And how do you generate one or the ...
0
votes
2answers
59 views
The potentiality of the electric field
Could you please explain using just words why electric the field is potentially? I know the proof using integral:
$$A = \int_{12}q\vec{E}\cdot{d}\vec{r} = qQ\int_{12}\frac{\vec{r}\cdot{d}\vec{r}}{r^3} ...
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votes
2answers
50 views
Voltmeter forming a closed circuit
A battery is connected to a 10Ω resistor as shown in Figure 2. The emf (electromotive force) of the battery is 6.0 V.
When the switch is open the voltmeter reads 6.0 V and when it is closed it ...
2
votes
1answer
110 views
How Special Relativity causes magnetism
So my physics teacher assigned us an article about how special relativity causes magnetism in a wire with a current, even with the low drift velocities of electrons in a current.
It seemed that the ...
2
votes
1answer
41 views
Why does increasing the temperature of a thermistor decrease it's resistance?
Surely, upon an increase in temperature, the atoms within the thermistor would vibrate with more energy and therefore more vigorously, hence making the electrons flowing through the electric circuit ...
1
vote
1answer
26 views
Speakers and Static from Hands
Why is it that when you touch the a bare male end of a speaker feed that the speaker makes hissing noises? Is it just (eddy?) currents running through you?
1
vote
2answers
74 views
Different batteries connected in parallel
If we have 2 batteries one of emf x and the other is of emf y and we connect them in series we get an effective emf of x+y.
But what if we connect them in parallel, how to calculate the emf now?
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votes
2answers
48 views
Do black holes have charges?
Do black holes have charges? If so, how would they be measured? Also, does electricity behave the same way? Black holes affect photons, which are carriers of EM radiation, so do black holes have any ...
1
vote
2answers
102 views
Simple ohms law on a battery ? Paradox or conceptual error?
Suppose we have a regular pencil battery which supplies DC voltage $V$. Say we take copper wire and connect the ends of the battery to an $R$ ohms resistance.
Then Ohm's law tells use the current in ...
4
votes
3answers
277 views
Why don't electric workers get electrocuted when only touching one wire? [duplicate]
I know that when electricians work on the poles on the streets, if they only touch one wire at a time they will be fine. However, from my understanding, the negative wire is connected to a large ...
3
votes
1answer
75 views
Why does the comb attract the pieces of papers if they're neutral?
When we rub our hairs with a comb, and then try to attract small pieces of paper, they're attracted by the comb. The pieces of the paper were not electrified before they were attracted. Then they ...
1
vote
0answers
12 views
Early Concepts in Relation with the Forces Produced When Certain Pairs of Objects are Rubbed Together
It was found centuries ago that these materials: wool cloth and paraffin wax, glass rod and silk cloth when rubbed against each other attracted one another. While two glass rods when rubbed against ...
0
votes
0answers
36 views
Electric Circuit with 3 objects [closed]
A light bulb designed to dissipate 75 W when it is connected to a 125-V source is in a circuit that also contains a 1850-W, 125-V hot plate and an 875 W, 125-V coffee maker. The circuit is designed so ...
0
votes
1answer
55 views
What types of materials can be electrically charged by rubbing?
What types of materials can be electrically charged by rubbing? Is there a certain type of materials in which static electricity can be produced by rubbing together two different materials?
1
vote
4answers
133 views
Capacitor Charging and Discharging when connected to the ground
When we charge a capacitor using a battery and then remove the battery, the plates of capacitor becomes charged. One holds positive charge and the other one gets equal negative charge. o. k. ?
Now ...
