# Tag Info

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Static discharge has a strong correlation with humidity. In winter, due to low temperature, the dew point is lowered and as a result, the water content in the atmosphere is lowered. In summer, correspondingly the dew point is higher and water doesn't condense as easily and so there is a lot more content of water in the air. Now the moist air being weakly ...

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As a general rule adding thermal energy doesn't cause electronic transitions. That's because typical electronic transition energies are a few electron volts or around 100kT at room temperature. In a metal the electrons aren't in discrete energy levels but instead reside in a continuous band of energy levels called the conduction band. While thermal energy ...

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Due to the cylindrycal shape of the lamp, pressure forces act compresing the glass. Since the compressive strength of glass is quite high, $\approx 10\,000$ bar, atmospheric pressure is not enough to break it.

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In electrostatics, we generally assume our conductors to be ideal. This indirectly assumes that charges have free mobility inside the conductor. You must remember that a system is more stable the lower its energy is. A system of free charges always tries to assume a configuration in which its potential is the lowest. (This configuration is achieved because ...

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You've asked some really good questions here. Before starting, I want to first mention that the traditional picture of particles moving through a wire in electostatics is missing some physics; for instance, it ignores the quantum mechanical nature of electrons. The reason we still teach this model is because it captures the main effects (the phenomenon of ...

2

The second equation is essentially a special case of Gauss's law and could refer to a variety of situations. The first equation happens to be a special case of the second equation. Gauss's Law says the total of the electric flux out of a closed surface is equal to the charge enclosed by the surface, divided by the electric permittivity ($\epsilon_\circ$). ...

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There are two aspects to your question. One is: "when I run across an artificial turf field with plastic soles, why do I accumulate static charge?" and the second is "When I am charged, why do I experience a shock when I touch a metal goal?". Taking each in turn: There is a phenomenon called triboelectricity - the generating of a potential difference when ...

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The current in a circuit is a collective phenomenon from zillions of electrons. It appears due to conductivity, another collective phenomenon . It is a cumulative behavior of atoms and electrons in matter. In insulators, electrons occupy energy levels and have to be actively kicked out of them, with the energy provided by an interaction. Insulators can be ...

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Most utility-scale (large-scale, the thing you've referred to as "government") generation is photovoltaic. Photovoltaics work on any scale, from watts to gigawatts. Whereas concentrating solar thermal generation needs to get a mass of fluid up to hundreds of degrees celsius, in order to drive a turbine. It's absurdly inefficient (in energy terms and ...

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The powerline can supply large amount of current, whereas the doorknob cannot. Each power supply comes with voltage and max rated current. Let us say body resistance is 5M ohm. Then current flowing through the body when you touch powerline is 20k/5M = 4mA. Now powerline can easily supply 4mA of current. But the doorknob cannot supply 4mA. So the actual ...

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The Key to your question is the distinguation between ideal and real sources of voltage and current. If we stay at the batteries: At the moment you attach batteries paralell to your body, what happens is that one part of the body has another electric potential than the other one, thus (Ohms law) a current will flow in your body. At this point the current ...

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The naive reasoning which leads to the conclusion that charges $Q_1$ and $Q_2$ of two touching conducting spheres with radii $R_1$ and $R_2$ are related by the relation $Q_1 = Q_2\frac{R_1}{R_2}$ is wrong. This formula holds only when the distance between the spheres $L$ is large compared to $R1$ and $R_2$, $L\gg R_1,R_2$, and the spheres are connected by a ...

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The helicopter and the power lines are at different potentials, the difference being so great as to cause the air in between to become a conductor. If you applied such a potential difference across a line worker it would probably result in death. You will note that the line worker is holding a metal stake which has a "pointed" end. This increases the ...

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In your last question it is important as to what you mean by WRT the question. If you are trying to find the E-field due to a point charge using Gauss then to make the surface integration easier you choose a surface which has the following properties: the E-field direction is everywhere perpendicular to the surface the E-field has a constant ...

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You are correct, electric current consists of electrons travelling from one place to another. Some materials conduct electricity better than others. Copper is one of the best and that's why our conductors are usually made of copper. Aluminium is also very good (so is silver) and high-voltage cables are usually made of aluminium. However, everything conducts ...

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If the bulb is lit when you pour water on it, it will undergo thermal shock. Some parts cool down and shrink, while other parts are hot. This causes very large thermal stresses, which can break the bulb. Depending on the material and construction of the bulb, this may or may not result in a spectacular implosion (once the bulb cracks, the vacuum inside will ...

2

I don't know the details of Apple's charging software, but this is almost certainly an artifact of the OS sensing the plug pulled out and taking its time to update the screen. Remember, when the device is charging a lot of processes happen differently (power saving mode controls everything from volume to brightness to which apps get priority), and I don't ...

1

A common example of this effect is when a car is started. In the case of a car the starter motor draws a very large current (100s amps) when it is switched on. The battery in the car, open circuit voltage $\mathcal{E}$, has an internal resistance $R$ and so when a current $I$ is drawn the voltage across the terminals of the battery will be $\mathcal{E} - ... 1 Given the phrasing of your question, I'm going to make a guess and say you're looking for an analogy to make sense of some information that is given to you. Let's talk about saws, like this chainsaw: Saws always cut by dragging the teeth of the saw across the wood, doing work. A chainsaw operates analogously to DC. The motor is applying a force to the ... 1 The reason to use the alloy is because it has a much higher resistivity than copper and so the alloy wire will have a higher resistance which with standard laboratory apparatus can be measured more accurately. I also seem to remember that the temperature of coefficient is lower for some of these alloys ie for a given increase in temperature the resistance ... 1 The basic principle: 1 volt is induced in a loop when the magnetic flux through the loop changes at a rate of 1 weber per second, i.e. 1 tesla times square meter per second. Provided you have a 1x1 cm loop, in a 0.5 T field of a pair of very strong neodymium magnets, and the loop has 100 turns, the overall magnetic flux through all the coil turns would be ... 1 The net effect of the charging process is the movement of electron from one plate which then has a net positive charge to the other plate which then has a net negative charge. The battery facilitates this by creating an electric field in the wires and it is this electric field which applies forces on the electrons which makes them move. The movement of ... 1 If you did not have resistor R in the circuit the voltmeter would always give the same reading - the voltage of the battery. A thermistor changes its resistance when a temperature changes. You are not given a resistance meter. All you have is a battery, a resistor R and a voltmeter. The circuit as set up is called a potential divider which means that the ... 1 It depends on the shape of the medium, but basically you could have an infinitesimal resistance,$\mathrm{d}R$, and integrate that. For example, for a uniform area wire of area$A$and length$\ell$in which the resistivity varied sinusoidally about some nominal value, $$\rho(x)=\rho_0(1+0.05\sin\left(\frac{5}{\ell}x\right)),$$ then$$R = ... 1 Each material has some internal resistance, so moving electrons collide with other electrons and release energy in form of heat. Read more 1 in this scenario, no electrons should be leaking from the circuit; and the number of electrons that enter the circuit (-) should be equal the the number of electrons that exit the circuit (+), am I correct? Energy conservation is not the same as charge conservation. The energy that electrons carry is determined by the circuit, an average drift velocity, ... 1 Although there are many free ions and electrons, I strongly doubt that it would be sufficient. Consider this: electrons always take the path of least resistance. If the atmosphere was that conductive, then the battery would just short out because the electrons would just go from pole to pole of the battery without going through the bulb. 1 It basically conducts electricity the same way salty water does: both contain some concentration of charged particles that are free to move. Water contains some concentrations of ions and protons (H$^+$protons). When there is a voltage difference, the ions will move according to their charge. The hot gas of the flame contains positively charged ions and ... 1 The first one is the force between two point charges and the second one is the electric field between two uniformly charged plates. Now you edited your post, so the first one is the electric field of a point charge$q\$.

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You can confine an electric field in a Faraday cage, if you want to, then the volume is finite. – CuriousOne

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