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

learn more… | top users | synonyms

-1
votes
1answer
17 views

Wireless energy flow through earths magnetic field

Seeing that technologies such as that developed by WItricity are based on magnetic fields, is it possible to transfer electricity that way through earths magnetic field?
0
votes
0answers
12 views

Show that the current in a cylindrical conductor is uniformly distributed across it's cross section

Using relevant equations for E and J, show that the current in a steady current I in a cylindrical conductor with uniform conductivity $\sigma$ is uniformly distributed across its cross-section. I ...
-3
votes
2answers
23 views

Long life energy usage

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. ...
0
votes
0answers
6 views

Biological Signal Extraction Methods

EEG / MEG Back in 1929 Hans Berger recorded the first electrical potential variations in the brain from the scalp. Great advances have been made in this science since discover, with many scientists ...
0
votes
2answers
43 views

Electric field 0 everywhere inside Gaussian surface

Gauss's Law shows that the electric field everywhere inside a spherical shell of uniform charge density is $0$. Suppose we have a surface which divides space into two disjoint regions (an interior and ...
-2
votes
1answer
29 views

How does the solar cell work?

As of i know that a solar cell consists of a transistor(NP) .First step it creates a barrier between the n type and the p type junction.Then following that the sunlight i.e,(the photons) supply ...
0
votes
1answer
33 views

Repulsion of electric charges

If a take a vacuum tube and put electrons in it and put a negative ion strip or something like that outside the tube will the electrons inside the tube start moving due to the repulsion of charges of ...
1
vote
1answer
34 views

Electricity is the movement of electrons or ions?

Electricity is the movement of electrons from one atom to another or the movement of charged negative particles (ions)?
0
votes
1answer
68 views

In what direction will this magnet move? [on hold]

What will be the direction movement of small ringshaped magnet when place inside the big ringshaped magnet with the same poles?
0
votes
1answer
49 views

Understanding the relationship between electric energy and force

I'm trying to do the following problem: One of the three types of radioactive decay is "β decay", during which protons decay into neutrons or vice­versa, emitting either electrons (β­) or positrons ...
1
vote
2answers
36 views

Why can't I connection the anode of a battery to the cathode of an other battery and get a current flowing?

If I touch the anode of a battery or connect the anode the the cathode of an other battery, none (or rather: a very small current) flows between those two. If I instead connect the connect the anode ...
0
votes
2answers
72 views

Derivation of Faraday's law using Lorentz force?

For a stationary loop of wire with a time varying magnetic field $\vec{B}(t)$ through it. Is it possible to derive Faraday's law, using only the Lorentz force $$\vec{F}=q \vec v\times \vec B \tag ...
-1
votes
1answer
47 views

What is an electric charge? [closed]

Can you explain to me what is an electric charge? In particular: Where is it? How does it look(in a figurative sense, I know that we can't see it)? What is inside the charge? I want to know ...
1
vote
1answer
28 views

current passing in primary circuit of transformer

When the secondary circuit is open ,why does the self induction found in primary coil would resist the flow of current in it? whereas in the small examples that I have taken in my studies from coils ...
0
votes
0answers
19 views

Non-linearity of energy conversion efficiency

I have a very general question to all of you. I am wondering if there is any basic physics principle that would state that energy conversion efficiency will be always non-linear (for the practical ...
0
votes
3answers
66 views

Which of the following has higher resistance - milliammeter or ammeter?

The question is the same as the heading - Which of the following has higher resistance - milliammeter or ammeter ? Now my teacher's and my answers don't match. It is assumed that the spring constant ...
0
votes
0answers
13 views

Static Electricity - Plastic comb, hair and small pieces of paper doesn't work for me?

All I have to do is run the plastic comb through my hair and hover it over small pieces of paper, right? The comb should then be charged and attract the pieces of paper... but that doesn't seem to ...
0
votes
0answers
64 views

Where do the electrons go?

In our house most of the plug-points have 2 holes. I know that one hole is neutral and other one supplies electricity. I can say that when i plug any device and turn the switch on electricity starts ...
1
vote
1answer
30 views

Static electricity experiment

My teacher always asks me to do the experiments on static electricity in winter. I don't know why? What will happen if I conduct the experiment in monsoon?
0
votes
2answers
68 views

What can happen when 2.3*10^28 positrons collide with 2.3*10^28 electrons? [closed]

I'm interested in this question after a writer friend asked me what happens when a human gets bombarded with positrons. Didn't want to post this under scifi because I want more "scientific" answers... ...
1
vote
1answer
24 views

Filament Lamp equation (Current/Voltage)

I'm starting to work with simple circuits (learning how to measure electromagnetic variables). I have been looking up on the internet for a formula or deduction of a formula that relates the current ...
0
votes
1answer
31 views

Can incandescent light bulb can be brighter if fixed power?

I found that luminous efficacy of 60 W tungsten incandescent bulb is 14.5 lm/W. Is this value defined by design details listed above or it depends on something else too? Can we design 60 W tungsten ...
-1
votes
0answers
10 views

Can this electrcity generated by a superconductor used for other purposes other than levitation? or together for both purposes

i want to ask whether the electricity produced by superconductor can be used up of other purposes other than levitating it, or can it be used for two purposes that are levitation and for eg lighting ...
1
vote
1answer
36 views

Why doesn't a levitating superconductor generate usable electricity?

Why doesn't a super cooled superconductor generate usable electricity due to the phenomenon of electromagnetic induction when placed upon a magnet? I basically mean, why can't it create electricity by ...
0
votes
1answer
37 views

Basic Conductor question

I have just taken a physics test in my high school in which one question posed that a positively charged rod is held near two uncharged spheres being held by silk filaments. Sphere 1 is held by a dry ...
0
votes
0answers
21 views

Why are trampolines more likely to give you a static shock when it is sunny?

It could just be in my head but I have noticed that I am more likely to get a static shock from my tramp when it is sunny than when it is not sunny. Is there a reason for this?
0
votes
1answer
49 views

Why is the potential difference across these two capacitors both 9V?

So above are two difference circuits, each with a 9V battery and a capacitor of the same capacitance. $C_1=C_2$ Why is the potential difference across both capacitors 9V? Shouldn't it be less than ...
0
votes
0answers
22 views

Potential difference on a curcuit

Above is a simple circuit. It has a voltage of 9V between the two terminals. I have drawn red lines which look like vectors, indicating how the current will flow. From the above diagram, I have a ...
0
votes
0answers
34 views

How would you define a difference in potential?

I'm currently in 12th grade, and am required to write an essay about physics and biology. The topic of the essay is the artificial brain (with the researches of the Human Brain Project in Switzerland ...
1
vote
1answer
80 views

Why do bowlers rub the ball before bowling in a cricket match

Why do bowlers rub the ball before bowling in a cricket match? What is the science behind it? Is it because of friction?
0
votes
1answer
46 views

Wait… why exactly does farady's ice pail experiment prove Gauss's law?

You'll notice there are no equations in this: that's because this is a question of morale, not of math. But a humble one at that! I come to learn, not to expound. But don't let that limit the form ...
0
votes
0answers
11 views

domestic lighting - live wire is live, neutral is not [migrated]

A ceiling light has failed and i have removed it. The circuit that it was part of (eight other downstairs lights) is working fine. BUT the supply cable from this circuit to the failed light is 'live' ...
1
vote
1answer
23 views

Is a CRT / Electron gun in need to be in a closed loop?

I'm trying to understand electricity and there for electrons. And so far i believe i am grasping it. But there are a few parts i have a hard time understanding. For example in as i understand it, in ...
0
votes
0answers
12 views

My electrophorus doesn't work

I have failed in generating charge using electrophorus. The charging material was a balloon rubbed with hair until it became very full of static, as well as a small piece of Styrofoam rubbed with the ...
0
votes
1answer
23 views

Electrical network of current sources - What happens if one source is defect?

Suppose you have connected in a parallel circuit a pair of, say for the sake of concretness 5 sources of 300 mA and 0,5 V each, which are themselves connected together in series. Hence, in total one ...
1
vote
2answers
42 views

A question about induced fields

This is something that I just realized bothers me, after thinking about it too much. Faradays law tells us a changing magnetic field creates a circulating electric field. This electric field has a ...
3
votes
1answer
313 views

What proved Conventional sense wrong?

What fact proved for the first time that the conventional sense of current was wrong? And when it did happen? As a corollary of this question, why do we say that electrons have negative charge? Is it ...
1
vote
2answers
82 views

Is there a formal proof for the superposition theorem?

I was just wondering whether there is a formal prove for the superposition theorem in electric circuits? I tried searching it online but couldn't find anything sufficient. Most of the sources assume ...
0
votes
0answers
20 views

Does triboelectric effect causes building up charge only on the surface of the material or inside as well?

I am planning on building a Van De Graaff generator and what I plan to use as material for the rollers is PVC for bottom roller(or Teflon), nylon (pantyhose) or wool for the belt and metal (conductor) ...
0
votes
0answers
11 views

What causes a larger (longer) electrical arc when using a tesla coil

So, I really don't know much about this subject, if any at all, but I'd like to do a project on it. I've done some testing with my tesla coil and there appears to be a trend such that a larger ...
1
vote
1answer
33 views

Help me understand static electricity

This is what I understand about electricity: (The following information is paraphrased from the book CODE by Charles Petzold.) Atoms are made up of protons, electrons and neutrons. Protons and ...
0
votes
1answer
55 views

How do I set up the Biot-Savart equation for the magnetic field inside a circular loop of current

The way I have derived the magnetic field for inside the current loop of radius $R$ is very different from how I have seen it online. Generally they take the equation for the magnetic field at a point ...
0
votes
0answers
20 views

How does current flow in the circuit during negative cycle of input?

So,as far as I know the input signal just controls the current from +Vcc as per this analogy But in the first picture during the negative half cycle of the input waveform the output wave form is ...
0
votes
2answers
65 views

Why can't mutual inductance create perpetual electricity?

Consider the following image. When the battery is connected then current starts flowing through the primary cicuit and magnetic flux changes through the coil, this causes electricity to be induced ...
0
votes
1answer
57 views

What material can achieve the highest temperature before failing when being heated by electricity?

Just as a qualifier, I barely made it through physical science in college, so... Please be detailed in your answers and assume I know nothing. Let's say I wanted to make an electrical coil for the ...
-1
votes
0answers
28 views

Gauss's Theorem in electricity and its gravitational counter part [duplicate]

We all know the Coulomb's law is the electrostatic counter part of the Newton's law of gravity.So by considering a gravitational potential,is there a gravitational counter part for Gauss's theorem in ...
0
votes
0answers
15 views

Temperatures reached in arc flashes

Good morning, I have a question regarding the arc flashes. Some papers mention that temperatures of nearly 20000 K can be reached during an arc flash. Could anyone explain how to come up with those ...
0
votes
1answer
21 views

charge density is a constant or a scalar-value function of position?

Since it is "density", I suppose that such values as charge density of a volume region $\rho_v$, charge density of a line $\rho_L$, and charge density of a surface $\rho_S$ is a constant but I ...
0
votes
3answers
44 views

Electric warning signs question

I've always wandered why do the warning signs show the voltage, not the current. I mean, it's the current that kills you.
0
votes
1answer
40 views

Electricity from effervescence, is it possible?

I've had this idea for quite some time (after having a cold and seeing Tabcin sparkling tablets), is there the possibility to generate electricity from effervescence? I envisioned something like the ...