# Tagged Questions

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

2k views

### Why does material resistance increase with temperature but electrolyte internal resistance decrease with increase in temperature?

The question is pretty much in the title itself, why does the internal resistance decrease with the increase in the temperature of electrolyte? Is it related to the electrolyte bring a fluid or ...
2k views

3k views

### Is a capacitor in an open circuit charged?

Say I have a circuit consisting of a battery, a wire, an open switch, and a capacitor. The circuit is open since the switch is open. My book says that the capacitor will only be charged when the ...
257 views

### Can resistance of wire be ignored

I was doing some physics homework involving direct current circuits and resistors in series, and I started to question the accuracy of the following property of resistors in series, namely that the ...
2k views

### Why doesn't the electric field inside a wire in a circuit fall off with distance from the battery?

We studied electric fields due to point charges. The magnitude of these fields decreases with the square of the distance from the point charge. It seems to me that we could treat the positive ...
2k views

### What is the current of a capacitor when the derivative of voltage is undefined?

This is from the textbook I am reading: I know this equation for capacitors: $$i=C\cdot \frac { dv }{ dt }$$ Here is my question: how can diagram (a) be allowed if the derivative of the voltage ...
391 views

### Current vs Voltage Drive for Loudspeakers [closed]

Please see this article: here I don't know enough EMFT to comment on this but I am working on other tasks for a wireless speaker system prototype called "Busker's Friend". Completing my Schaum's ...
110 views

### electron levels in a high voltage conductor

what is the electron energy level in a 300,000 volt power line? This voltage is way above the ionisation potential but electrons are not emitted from the wire.
98 views

### Conduction and propagation [duplicate]

What is the difference between conduction of electric wave in conductor and propagation of electromagnetic wave in dielectric? Why propagation term is used for dielectric and conduction for conductor?...
4k views

### Charge of an electric wire

If an electric current is flowing through an electric wire, can we consider that wire charged? The answer is required with a proof. Can we consider the wire to be charged positively or negatively?
166 views

### Is it possible that a battery goes flat faster in a cold environment?

I own an old iPod Classic with original lithium-ion polymer battery and I use it primarily while running. Recently I discovered that when a temperature outside is low, usually below 5 C degrees, the ...
527 views

### Why doesn't alternating current produce light while a vibrating single particle with a charge will

If a vibrating atom can produce light why can't an alternating current of electrons do the same? EDIT: When I use the term "light" I mean all EMR
150 views

### How do inductors produce current?

This is how I understand batteries and capacitors. The terminals produce an electric field which causes the electrons to move in random directions. The surface charge builds up causing new electric ...
56 views

### How much electricity can be generated from ambient sources?

I know that recent advances in technology are doing amazing things with very low amounts of electricity, with RFID being one of the most familiar examples, but I'm not very familiar with the ...
108 views

### Energy in a Solenoid?

Consider a circuit consisting of a battery, a resistor and a solenoid inductor. Then, the emf $\mathcal{E}$, is defined as: $$\mathcal{E} = L\frac{di}{dt} + iR$$ Multiplying both sides by $i$...
227 views

### Inductance of a solenoid?

My textbook is using Faraday's law to explain the self inductance that happens in a solenoid with changing current. According to Wikipedia, Faraday's Law is: The induced electromotive force in ...
789 views

### What happens when you pass a current through a coil made of a ferromagnetic substance?

I know when you pass a current through a length of copper coil or a solenoid, there is the induction of a magnetic flux. But what of the coil made of the ferromagnetic material, the permanent type ...
125 views

### What is electricity?

What is electricity? I know very little physics. I know that there are neutrons, positively charged protons and negatively charged electrons in a particle. I know that electrons have some role in ...
346 views

### Voltage Drop and Charge Flow

I am hoping someone can help me with understanding voltage drop and charge flow. Here is what I think I know. The voltage drop through a circuit must equal the voltage of the battery source, and ...
33 views

I'm a total novice to physics so please forgive me but I'm looking for a starting point on sound, frequencies and everything to do with electricity. Preferably books because my internet usage is ...
538 views

### How does electricity flow?

The terminals of the batteries set up an electric field in the wire. Surface charges build up to ensure the field is perpendicular to the wire. This allows the electrons to move through the wire. But ...
477 views

### Batteries and voltage?

The voltage of a battery gives you the difference in potential energy 1C of charge would have at the positive terminal vs the negative terminal. If I connect a wire to both terminals, the battery ...
181 views

### Why are free electrons always moving?

Electrons move when a field acts on them. If the electrons move towards the field, they cancel out the field when enough electrons build up. Shouldn't the free electrons stop moving eventually and ...
1k views

### Why does welding produce UV light?

Looking directly at a welder is dangerous because large amounts of UV light is produced. What makes this light? Is it electrons from the current that excites metal atoms, and these atoms sends out UV ...
499 views

### The effects of reversing the leads of an ammeter

I was playing around with a battery, an ammeter, and a light bulb. The ammeter originally read 1.99 A, but after reversing the leads going into and out of the ammeter the ammeter read -1.98A. I know ...
241 views

### Different phase in capacitively coupled RLC circuits

I was trying to work with some data for a lab report I'm writing about capacitively coupled RLC circuits. The setup is pretty simple and looks like that: Where $C^{'}$ is the coupling capacitance. ...
31 views

### electric charge is a intrinsic property how is there a prpoer way to explain electric charge? [duplicate]

how to define electric charge ? How to explain this term ? As learned by me electric charge is an intrinsic property of atoms like mass of different atoms.
295 views

### Is R1 R2 and R3 parallel? [closed]

or R2 and R3 are parallel then they are in series with R1?
709 views

### Why is no EMF being induced in this ring passing through a magnetic field?

The book's logic is that there is no induced EMF because flux is constant as it passes through the magnetic field. Which makes sense, but this seems counter-intuitive to what I previously learned. ...
3k views

### When mutual inductance is occurring between two coils, is self inductance always occurring in each individual coil?

When a coil connected to an AC generator creates an EMF in another nearby coil (mutual inductance), is self inductance simultaneously occurring in both coils?
195 views

### Electric field produced by a charged ring

I have a question I couldn't find an answer for anywhere. There is a ring of radius $R$ which is charged uniformly with linear density $\lambda$, and I have to find the electric field on any point of ...
815 views

### (Why) would unmaintained water heater use more electrical energy?

I'm specifically thinking about lime/sedimentation at the bottom of water heater, and calcification of heating elements (and not possible thermal insulation deterioration). It is very often claimed (...
383 views

### Explain the microscopic nature of Electric current?

Explain the microscopic nature of Electric current?i.e What is is average current and Instantaneous current? A microscopic view what really happens?