Tag Info

20

You can use a high vertical tube to store water in it (fill it from the bottom by pushing the water in) How much water can you store? It obviously depends on the pressure you apply to push it in. If you push harder, there will be more water stored. The tube is characterized not the amount of water, but by how easy it is to store the water. Its "capacity" ...

5

The energy of an electrical wave certainly undergoes energy loss through heat, so in that way is entropic. This is a result of the material's resistivity through which the electricity is conducted. The mechanism is primarily scattering of the energy through electron-phonon interactions, but electron-electron interactions do also occur. In metals, the main ...

4

You are misunderstanding. ELECTROSTATIC FIELD inside aconductor is zero, not electric field. ELECTROSTATIC field means the electric field created by charges at rest.We can understand this property by considering a conducting slab placed in an external field E. We can argue that the electric field inside the conductor must be zero under the assumption that we ...

4

Capacitance is "charge over voltage" – and one farad is "coulomb per volt" – because the capacity of capacitors (something that determines their "quality") is the ability to store a maximum charge on the plate ($+Q$ on one side, $-Q$ on the other side) given a fixed voltage. When you try to separate the charges, you unavoidably create electric fields ...

4

An easy way to determine whether there's current passing through the person or not is to look at the voltage difference between the two points that this person connects to the circuit. Because the difference in voltage is the reason of current passing through. (Same as no water pressure difference, no water flow) When touching a wire with two hands, because ...

3

This question appears to be a pseudo-duplicate on the Skeptics exchange, as pointed out by @CraigGidney. The highlights of the comments here and answer there appear to be that: 1) Yes, one could potentially accrue some electricity from soil. 2) No, it would not (ever) be sufficient to charge an iPhone, let alone 3 times. 3) In the comments here, "there ...

3

Theoretically, yes. The problem is that there's no way to build a "small" thermonuclear warhead. Fusion isn't as simple as fission, the latter being as easy as smacking the right amount of Plutonium together. It is technically energetically favorable to fuse heavy isotopes of hydrogen into helium, but the conditions required to do so include giving the ...

3

While the other two answers are technically correct, they are not actually addressing the engineering aspects of what comprises a "good" capacitor. Ideal capacitors in parallel or series circuits lead to ideal capacitors of different value, i.e. there is no measurable "quality" difference - ideal is ideal. In reality, of course, there are no ideal ...

3

At the power station electricity is generated as work from a heat engine. Work is entropy free, so we have an entropy free electron-gas at the point of generation. However, a thermodynamic gas will always equilibrate to the available degrees of freedom. In this case it is the electronic states of the conductor in the transmission wire. There will be a ...

3

The induced EMF in the disc produces a current - an eddy current. The current in the the magnetic field gives rise to a force that, in accordance with Lenz's law, opposes the inducing action.

3

They are actually sine waves. You can see this, for instance, if you put an oscilloscope across the mains (disclaimer: don't do this unless you know what you are doing and you know the scope and probe are rated to hundreds of volts). There is usually quite a lot of distortion and noise on the waveform which arises from both the behaviour of the generator and ...

2

The electromotive force generated in the power plant as a sinusoidal pattern with frequency of 50 or 60 Hz. Generally in the generator, the rotating motion of the magnetic rotor leads to sinusoidal variation of EMF in the winding of the stator and consequently in any circuit connected to the it. The EMF induced in the coil at any instant of time depends ...

2

A battery is both a sink and a source of electrons. It provides no net contribution of electrons to the external circuit, however. In the below schematic of an alkaline battery, which is a representative battery configuration: #3 is the metallic zinc anode #4 is a separator that conducts ions, but not electrons #5 is the nonmetallic manganese oxide ...

2

A closed surface like a sphere encloses some volume. Anything coming out through the surface (the net outward flow which we call the flux) will be in the expense of what remains inside. If the sphere encloses some charge, then electric field diverging out from the volume containing the charge will be equal to the normal component of the electric field lines ...

2

To increase the glow of bulb you need more energy. So increase the emf. However mind that the value of current should not exceed the current rating value of the bulb. You should be careful not to use emf inappropriately. Emf is the energy given by the electric source (here the battery) to the charges per unit charge. Otherwise it's the energy given per unit ...

2

The difficulty is that there are three voltages involved. The voltage at the power station end $V_S$, the total voltage drop across the cables $V_L$ and the voltage at the consumer end $V_C$. The voltages are related as follows. $V_S=V_L+V_C$ So you have power supplied by power station is equal to the power lost in the transmission cables plus the power ...

2

How can you do that when Vs and Vd are two different parameters? One must keep track of the variables. The power delivered to a resistor is $$P_R = V_R \cdot I_R = V_R \left( \frac{V_R}{R} \right) = \frac{V^2_R}{R}$$ where I have subscripted the variables so it is clear that the voltage and current variables are the voltage across and current through ...

2

The battery is an energy source that supplies the electrical energy to the electrons in the conductors. There is no actual flow of electrons. It's the energy that is transferred. A conductor contains large no. of atoms tightly packed with plenty of availability of valence electrons that are ready to move out from the atom if you supply a little bit of ...

2

The reason is that all experiments known can be explained by having two types of electric charge. To distinguish between the two types of charge them it is necessary to introduce labels, conventionally the labels were taken be "positive" and "negative". Because of history, electrons are given the label "negative".

2

The current induced in the coil will produce a magnetic field that opposes the spinning magnet. I like to demonstrate this with a hand cranked generator. With an open circuit no current flows and it is easy to turn the crank. Once you hook a small light bulb up to the generator or, even better, short circuit it, it becomes noticeably more difficult to ...

2

a giant air tank. if the tank is large enough, we could set off a bomb inside without exceeding the containment strength of the perimeter, then harvest power from the increased pressure in the tank. i imagine making a large air-tight tank might be cost-prohibitive, although a 19 million cubic foot tank is already in use. perhaps we could build a ...

2

As you say, the problem is confinement (aka containment) - fusion is relatively easy; controlled, useful fusion turns out to be incredibly difficult and expensive. So the easiest way to harness it, and the only technically and economically viable way (for decades from now, and possibly a century or more into the future), is to have a large fusion reactor in ...

2

This was actually considered under the Plowshare project The idea being to use an underground nuke to heat the surrounding rock and then run it like a geothermal resource. However, radiation problems.

2

Maybe it is worth bringing a comment into an answer: Batteries have protective circuits. The most basic safety device in a battery is a fuse that opens on high current. Some fuses open permanently and render the battery useless; others are more forgiving and reset. The positive thermal coefficient (PTC) is such a re-settable device that creates high ...

2

For copper the temperature coefficient of resistivity is $3.9\times 10^{-3} \text{K}^{-1}$ and the temperature coefficient of thermal linear expansion is $1.6\times 10^{-4} \text{K}^{-1}$. They differ by a factor of about 24 so a change in temperature will cause a bigger change in resistance than in the linear dimensions of copper. Resistance is given by ...

2

Induction current and displacement current are similar though, but very different terms. Induction current is the normal electric current but displacement current is the term which is only defined by Maxwells' equations. Now generally capacitors have a dielectric material between the +ve and -ve plates. When the capacitor is charged, there exists a strong ...

2

We Use $C=Q/V$ because those were useful things to measure. It's often easy to forget, but many of the equations we use are chosen because the work, and because other equations didn't work. Never underestimate that part of the reality. We don't use "charge per unit volume" because that number is not constant. You can charge a capacitor up without ...

2

I understand that capacitance is the ability of a body to store an electrical charge and the formula is $C = {Q \over V}$ Perhaps you just need to top thinking of capacitance as that. "Capacitance" sounds like "capacity", which leads to an intuitive trap like this: If I have a basket with a capacity of 2 apples, then a basket with more capacity can ...

2

A capacitor is used to store energy in form of electric fields. This electric field is created by charges on plates of capacitor. So, basically you are storing charge on capacitors. Let someone ask you how much charge you can store in your capacitor.What would you reply? Clearly , you reply " I may store 1mC or 100mC, depending on Potential difference ...

2

The man will NOT die in both the cases. Lets see it from the perspective of current. Imagine that you are the current travelling in the wire. You have to move from point A to point B (Let A and B be the position of contact of the man's hand with the wire) . You have 2 choices. First, you can go through the wire with low resistance to stop you. Second , you ...

Only top voted, non community-wiki answers of a minimum length are eligible