# Tag Info

## Hot answers tagged electricity

23

If there are charges being setup in the wire, the charges(electrons) have mass and cannot move at C. How then they don't affect the speed of electricity and gives us its speed to be equal to C. They do affect the speed. The speed of the signal in a cable or other communication channel is given by the velocity factor which is the speed of the signal ...

7

Electrons don't need to bump into each other to transfer movement, like billiard balls. They are charged particles which interact with each other at a large distance through the electromagnetic field. Imagine a room packed with balloons: if you push on balloons on one side of the room, the wave travels several meters to the other end of the room in a matter ...

7

Piezo electric cells convert mechanical energy to electric energy

7

Doesn't a battery do this? Also, capacitors. EDIT: With the edit, it looks like the premise of your question could be satisfied by a Van de Graff generator: https://en.wikipedia.org/wiki/Van_de_Graaff_generator which uses friction to strip electrons from a substance, and create an electrostatic potential.

7

The information about the disturbance of static charge equilibrium (toggling the switches) travels at the group velocity of light in matter, which is in turn related to the refractive index in matter, or more precisely to its dispersion (rate of change of refractive index with frequency/wave number). Group velocity is sometimes close to the speed of light, ...

3

$11 W$ means the bulb uses 11 watts of power when it's operating at the rated voltage. If you run it for an hour for example, it will cost $0.011 kWh$, and your power company will bill you for ___ (check your local electricity prices). You can also calculate how much current the bulb will draw since you know the voltage, as well as the resistance of the bulb ...

2

Yes Newton's law is applied here, and the electrons accelerate in response to the electric field. However, the electrons also undergo collisions with the atoms of the conductor, so on an average, they acquire an initial velocity of zero just after each collision. The electrons then acquire a final velocity $\vec v_f$ before the next collision and the average ...

2

There are several errors in your analysis: The equivalent circuit of a voltmeter is not the one you represented: a real voltmeter should be represented as an ideal voltmeter, with infinite input resistance, in parallel with the voltmeter's input resistance ($R_2$ in your case), not in series. The correct value of $V_{C_\mathrm{max}}$ is $$V_{C_\mathrm{max}}... 2 Always when I study displacement Current it is zero outside the capacitor because the electric field is zero outside That is "mostly true". The field created by a charged capacitor is mostly contained between the plates of the capacitor. However there are "fringing" field lines, and a very small amount of field will go from the outside ... 2 Disclaimer: electricity is extremely dangerous. Please don't play around with your home's main electricity. You could badly injure or even kill yourself. This is especially the case if you live in a country that uses 220~\rm V or higher. There are a lot of things that can factor into you receiving an electric shock or not. But the general idea is that you ... 2 The electrostatic potential is defined by \vec{E}=-\nabla V and the definition of electric field is the force on a charge divided by the magnitude of the charge. Alternatively if you want to think about this in terms of energy, you can use the definition U=qV. It can be proven from the principle of least action (an axiom) that -\nabla U = \vec{F}, ... 2 The model of a magnetic field induced by current that one generally sees in a textbook is based on an equilibrium, steady-state condition. In a dynamic situation, the magnetic field will be more complicated. Once one part of the wire has current flowing through it, all of the wire can have some magnetic field around it; the magnetic field doesn't stay just ... 2 I wouldn't say so, no. Firstly, the key difference between a capacitor and a typical battery is the state in which the energy is stored. A capacitor is the only device that can be said to store "electricity", meaning what is being stored is the actual charges and charge separation on two plates. In a battery, the energy content is stored ... 2 Initially, there is a radiating electric field radiating out of the left hand sphere, and no field from the right field. The electrons that first move from left to right are acted upon by that field. So, your assumption that no work was done on them Is incorrect. As electrons move from left to right, the left field will weaken and the right field will grow.... 2 Yes, the current depends on the internal resistance. And that resistance has been adjusted to give a current that corresponds to 11 W. (By the way, note that we typically don't symbolise the wattage, the power, with W but rather with P.) 2 To answer your title question, the speed of electricity does not become the speed of light. But many "messages" or, more correctly, transient effects that set up the final steady state flow do indeed travel at the speed of light in the medium your circuit is steeped in Think of your circuit at the very instant you close the switch. The switch ... 1 electrons move from a region of higher concentration to a region of lower concentration, so due to that they didn't needed any external energy supply like potential difference That isn't true. The reason electrons or negative charges moved to the uncharged conductor is not because their was a concentration difference but rather because they were at ... 1 The question is a bit vague, however here is a possible explanation: There are at least three sorts of light bulbs: The oldest models with an incandescent filament. The early economical bulbs which are discharge lamps in disguise (with a discharge tube coiled inside a bulb). The current power saving bulbs using semiconductor diodes to produce light (i.e. ... 1 Your second equation holds just for all series RCL circuits. And we are assuming sinusoidal currents and voltages. Otherwise, not much wrong that I can see, now that you've put right the typo. Note that rms values can be used throughout instead of peak values if you wish. 1 To a pretty good approximation, your skin is a conductor; charge can flow over your skin pretty easily. This means that any differences in electrical potential at different points on your body will get evened out as the charge flows across your skin, and you can talk meaningfully about the "electric potential of your body". This also means that ... 1 Any stream of charged particles like electrons and protons and ions moving trough a medium or vacuum can be called as electric current. It's up to you to define what you call current and what you call electrical dscharge. In a close circuit, the battery supply energy (by electric potental difference) for electrons to move in the circuit. Electrons move ... 1 With the battery - you need a conducting material. For a charged particle to feel a force? Nope, you dont. There's still an E field inside the battery just like in your picture above when there's no conducting material attached. When you attach a conducting material though, charges will get pushed through it. Those charges obviously have their own E fields, ... 1 Batteries create a potential difference through chemical reactions inside the battery. Many chemical compounds are made up of ions, which are groups of atoms which have exchanged some electrons with other groups of atoms. For example in sodium chloride (the "salt" you use in cooking) each sodium atom loses one electron, and each chlorine atom ... 1 So if I touch only one of these poles, will I get shocked? No. If two conductive bodies at different potentials make contact, current will flow which will attempt to equalize their potentials. Because you are only touching one terminal of the battery, all of the charge that may flow into you will have the effect of bringing your potential closer to that of ... 1 The negatively charged plate is not necessary. What it does is make the field between the plates uniform, which makes it convenient for treating the problem mathematically. As for your other question, yes! The electric potential is a field. That means it has a value at every point in space, be it inside a wire, the air around you, or in your body. The very ... 1 11\rm\,W means that at its working voltage, on average over a period electrical energy is converted into other forms of energy, heat and light, at a rate of 11\rm\,J/s. One has to be careful when quoting the resistance of a light bulb as a bulb's resistance depends on the applied voltage with a higher applied voltage increasing the temperature of the ... 1 The electric field inside a wire depends upon the the current density according to the microscopic version of Ohm's Law.$$\vec{J} = \sigma \vec{E}$$where \vec{J} is the current density, and \sigma is the conductivity of the material of which the wire is composed. If the cross section of the wire is increased, the current density will go down, and as ... 1 The question assumes an ideal battery. An ideal battery is a current source with fixed voltage (V) that always satisfies Ohm's Law (V=IR) by supplying the required current:$$ I = \frac V R  NO MATTER WHAT. That is what "Ideal" means. The question goes on to state that $R=0$, which requires infinite current. At this point, any discussion of ...

1

Circuit theory is best described by the Classical laws of people like Ohm, Faraday and Maxwell. Photons of electromagnetism only come into the picture at the detailed quantum level when explaining things like the photoelectric effect, and even there the main message to take away is energy threshold levels. Electrons from a battery are pushed along a wire by ...

1

One has to keep clear that there are two kinematic mathematical frames to model particles: a) the classical mechanics frame and b) the quantum mechanical frame. Now, it's generally taught (and even visualised) that atoms are like balls which bump when collided with other atoms. This is the classical mechanics frame. And it's also said that electrons ...

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