The study of the presence and flow of electric charge. Charges, currents, fields, potentials.

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Finding the direction of magnetic force acting on a conducting wire

I have a problem in finding the direction of the force when a conducting wire is placed on a magnetic field. If i use Flemings Right hand rule I get circular magnetic field so what will be the ...
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2answers
13 views

Unequally charged hanging pith balls

I have done a problem which asks us to find the charge on two equally 'massed and charged' pith balls which are left hanging on a string with a certain length that repels each other and attains an ...
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17 views

Direction of current in concentric cylinders

Example 7.2 in David Griffiths E & M book (3rd edition) has a side view of 2 concentric cylinders, with smaller radius $a$ and larger radius $b$. The region in between $a$ and $b$ has ...
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Electricity Problem [on hold]

A power Station Is Connected To A Factory 2.5 km Away By Two Wires the potential difference between the terminals of the wires at the station is 240v and that for the other terminals at the factory ...
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42 views

How can metal objects become electrically charged, if current flow means that an equal number of electrons enter/leave the object?

I am trying to answer to the question in the title. I am restricting my question to metal objects only. Here is my logical reasoning: Current is the flow of charge over time. In a circuit (simple ...
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22 views

Inductor Charging and Discharging

Why does the inductor discharges in the same path ( same direction of current ) as that of its charging unlike a capacitor which discharges in the direction opposite to its charging(current direction ...
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2answers
57 views

How can a fruit be used as a battery cell?

Fresh fruits can be used as batteries for glowing bulbs, but how this is possible? I mean how can electric charges flow through fruits? Do they contain chemicals like cells?
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Electricity Conductor [on hold]

Which is the good conductor of electricity among these? Tap water. Sea water. Please send answers today itself. Its very urgent.
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157 views

If atoms have specific energy levels, why do opaque solids absorb all visible light, not just some? [duplicate]

Here's my question: if atoms have well defined energy levels and those differences correspond to the frequencies of light that can be absorbed, how is it that opaque objects absorb all or most visible ...
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41 views

How are the names of electric components given? [closed]

How are the names of electric components (e.g., diodes, transistors, transformers, relays, etc) given to them?
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46 views

How can a glass rod become charged if it is an insulator?

I was reading some of the other questions, and I found this one about a glass rod and how it gains a net charge when rubbed with a silk scarf. I learned from working in a shop one summer that most ...
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1answer
57 views

Alternate method of transmitting wireless electricity?

I have currently been researching a lot lately about wireless transmission of power. Currently the only methods i have seen that is viable is magnetic induction, and high voltage discharge(tesla coil ...
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4answers
116 views

How to measure the energy consumption class of a home appliance? [on hold]

Some of you may be familiar with the EU energy consumption classes for domestic appliances (or equivalents in other areas). Let's say we have a domestic appliance which was made before the energy ...
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44 views

Circuit breaker Trips during thunderstorm

The circuit breaker at the electrical mains trips at home when there is a thunderstorm outside. Why does this occur?
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1answer
32 views

When the magnetic force is perpendicular to the velocity what will be affected on a charge? [closed]

I guess it can also be stated as a two part question. Is the velocity of a charge always perpendicular to the magnetic force, and when the magnetic force is perpendicular to the velocity what is ...
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4answers
76 views

Why wire filament shakes inside a light bulb?

My light bulb cast a clear light toward adjacent wall and I can clearly see, that wire filament inside bulb shakes, though lamp itself does not moves even an inch What is causing this? Is it a ...
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0answers
34 views

Physical interpretation related to a non-linear partial differential equation

I am doctoral student in pure mathematics working on a particular problem. My question is if this problem has applications to real world phenomena. I will try to explain the direct problem starting ...
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1answer
43 views

What physics considerations direct the charging of cars with wireless?

Is there any frequency at which cars can be charged with using wireless? Surely, wireless transmission can be safely assumed to be a form of energy transfer, and there can be charging of cars without ...
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1answer
29 views

How does electric field intensity look like along a wire which has one end connected to an AC source and the other one is left free?

How does the electric field intensity look like along a wire with constant conductivity which has one end connected to an AC source and the other one is left free? I mean is the electric field the ...
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0answers
32 views

Explain the infinitude of magnetic flux about a finite length of wire

Ok so it is clear the flux caused by an inductor is limited. If I integrate about a flat spiral inductor I will find that the flux lines going up are a fixed quantity. Since every flux line going up ...
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18 views

How to check the ohmic contact to the film?

I have a thin semiconductor film deposited on an isolating substrate. I would like to check different metals to find out do they form the ohmic contact or Schottky barrier. What is the best way to do ...
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1answer
17 views

Conductivity of Aqueous Ionic Solutions as a Function of Time

It is well-known that an aqueous ionic solution can conduct electricity. Let's take the electrolyte NaCl for example. In the diagram below, the circuit consists of a voltage source, a light bulb, and ...
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0answers
16 views

Make an Electric motor work with help of 4 magnet wheels? [closed]

I am working on a car prototype that should work on the electricity that it generates with the help of magnets. The strong magnets will be fixed at the wheels. A Coil of thin copper wire(solenoid) ...
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3answers
61 views

Potential difference (PD) and electromotive force (EMF) in terms of electrons?

I am trying to understand potential difference and electromotive force in terms of electrons. In the above 3 circuit diagrams the red shows (what I think to be) the distribution of electrons ...
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2answers
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Can I calculate the current of any setup with capacitance by the same formulae?

There are known formulae relating a capacitor's voltage and current in its classic form (battery, wires, a capacitor circuit), but what if we had a charged plate (-ve), then we put on one of its ...
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Since cables carry electricity moving at the speed of light, why aren't computer networks much faster?

Why can't cables used for computer networking transfer data really fast, say at the speed of light? I ask this because electricity travels at the speed of light. Take Ethernet cables for example, I ...
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1answer
49 views

Ambiguity on the notion of potential in electrical circuits?

As everybody else I have been taught elementary electrical circuits from secondary school to engineering level in analog electronics at university. Invariably, the notion of potential used to ...
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290 views

How does the movement of electrons produce radio waves?

I'm mostly wondering about radio frequencies. I understand that voltage is the movement of electrons, and that the antenna acts as a light bulb, emitting at radio frequencies, following the reverse ...
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1answer
32 views

Formula for Electrical Arc Length

I was playing with some High-Voltage the other day, when a question popped into my head. Can you calculate length of an electrical arc? It probably would be proportional to :- 1. Voltage of the source ...
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1answer
50 views

Electricity supplication [closed]

Is their any reason I can search up as to why electricity is generally harder to inaugurate in regions of vast inhabitability?
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15 views

Does the skin effect and the proximity effect cancel each other out?

I'm interested in how the Skin Effect and the Proximity Effect interact with each other. From what I can understand: The Skin Effect is when AC current 'collects' on the skin of conductors due to ...
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1answer
82 views

If light is an electric and (magnetic field), how can it be absorbed?

I was wondering how light or any electromagnetic radiation can be "absorbed" if it consists of electric and magnetic fields. For example if there is a charge at point A, and the light reaches point ...
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4answers
75 views

Why does a Resistor cause a potential drop?

I need to know the underlying physics of what exactly happens different with the electric field in the resistor than in superconducting wires. Why is it that when I connect a resistor, potential ...
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2answers
143 views

Why does smashing a TV remote load its batteries?

Many times I had the same problem: my TV remote's batteries were too weak for it to operate, but then, when I shook the remote a bit and smashed it on my palm, somehow the remote regained its ability. ...
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40 views

Electricity production

Are there alternate means to produce electricity than magnetic induction? I observe that all places this method is used .Do other methods exist even if this being the most profitable way.
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Basics of Current Electricity

I have certain questions which confuse me a great deal. I want to have a very basic and clear idea about some concepts. Here it goes: 1) I am really confused on how a battery actually works. The very ...
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Why is low resistance beneficial to ion exchange membranes?

http://scitation.aip.org/content/aip/journal/jcp/139/11/10.1063/1.4821161 The article states that the graphene filter has a much lower electrical resistance than existing ion exchange membranes, ...
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84 views

Why does resistance increase with length?

This is for the case of wires only (pipes are easy). I see that if I place a 9-Volt (constant) battery across any wire, the current is proportional to resistance. I don't understand why, for a ...
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2answers
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Drude model: A concerning approach to $\tau$ hurts Ohm's Law

Here's the question. Between two points, $a$ and $b$, if an object is accelerated between them, it will cross the distance between them in time $t=\sqrt{2\frac{d}{a}}$. So, if the acceleration is ...
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1answer
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Repulsion and attraction of electric currents

Now, I understand that when a an electron travels, it creates a magnetic field. If you put two wires with current traveling in the same direction they repel, and current traveling in opposite ...
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1answer
88 views

Why isn't resistance proportional to distance squared

Here we have a wire. At both ends there is an equal and opposite field caused by a chemical reaction. So, if we decrease or increase the distance between the two points, the strength of the field ...
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59 views

The measurement of electricity

I'm a student trying to understand electricity. As I learned from school, electricity is the flow of electrons, but I'm confused about the measurement of electricity. As I learned, voltage is the ...
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69 views

Curious about this perpetuum concept

I know it's not possible to build a perpetual motion machine, but I still got this concept running in my mind. If you take a (longer)copper coil, and insert an axis through it(right-angled) with a ...
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2answers
109 views

Heat loss using alternating current

I am looking for somebody who can explain this to me. As I have read in physics books, the Joule-Lenz Law (Joule effect of heating) is represented by the formula: $$ W = I^2Rt $$ which can be ...
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1answer
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Is it possible to overload a lightning rod?

A couple of weeks ago we had a big storm roll through the Chicago area. I watched as the city's skyscrapers were struck multiple times by lightning throughout the night and told my coworker about it ...
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1answer
61 views

Why is the perfect obstructor the perfect conductor as Heaviside 'believed'?

How might one consider a conductor to be an 'obstructor'? Might the strength of the 'skin effect' of a conductor be in direct relation to conductance? And how does this relate to insulators, as ...
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30 views

transfer of electricity through electromagnetic waves

Is it possible to transfer electricity from one place to another without the help of physical wires.
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3answers
59 views

What really is resistance? How does it generate heat?

OK I know that R= V/I. I also know that R = ρl / A But what I want to know is that what really causes resistance? Is resistance equivalent to force? or is it just a constant? Also, what causes ...
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2answers
81 views

Can we pass electricity through air?

Electricity: I was wondering, whether we can pass electricity through air over a distance of 100 meters or so as electricity means the flow of electrons and we have seen the discharge or movement of ...