# Tag Info

2

Make make an analogy between gravitational potential energy, which is easy to visualize, and electrical potential energy. By doing this all the knowledge they have about a simpler subject will help them understand a more complicated one. Hold a ball and drop it. Draw what happened on the board, showing that the more potential (voltage) the fastest the ball ...

0

The Kelvin temperature scale is an absolute temperature scale. That is 0 K is absolute zero. It also has the property that temperature intervals on the Kelvin scale are the same as on the Celsius scale. That is a decrease or increase of one degree Kelvin is the same as a decrease or increase of one degree Celsius. To meet these two requirements it is ...

1

What's true is that it's law of conservation of energy. It particularly states: Q= Del(U) + W, U: internal energy. That is, the total energy given to a system does two things, first it makes the system do the desired useful work and second it changes the internal energy of the system. The work can be positive or negative according to W=q(dv). Example: ...

-1

The previous answer, in my opinion is half-baked. The use of the delta term is quite misleading, as pointed out in the comments. Now, according to almost every leading textbook and my Professor, who is also a leading author, the I Law of Thermodynamics can be stated as: Q = ΔE + W where Q is the heat transfer across the system boundary, W is the work ...

3

Why do we use capacitors when batteries can very well store charges? There's an important point that, so far, I don't see in other answers. Neither of these devices store charge! A "discharged" battery or capacitor contain the same net quantity of electrical charge as a "fully charged" battery or capacitor. What they are "charged" with is energy, not ...

2

response function = susceptibility = (pure or mixed) second derivative of a (Helmholtz, Gibbs, etc.) free energy. Magnetization is not a response function as the free energy is not observable, so one cannot observe the response to a change of some variable.

2

A capacitor stores charge on a pair of plates. A battery generates charge through chemical reactions that break neutral atoms into positive and negative ions. Both store energy. A battery stores chemical energy. A capacitor stores potential energy in the separated charges. Sometimes a capacitor has an electrolyte between the plates. This is a molecule ...

2

batteries are a much more efficient at storing electricity but in circuits, it makes much more sense to use capacitors in circuits as they are much more efficient for the short term storage of electricity. batteries are a lot more bulky and to work as a capacitor they would need to be rechargeable. it would not make sense to have two batteries in a single ...

4

While a capacitor can be used to store charge, usually we are interested in other properties. Most notably, it has a voltage proportional to the amount of charge stored ($Q=CV$) which means it acts as an integrator of current. There are many circuit applications where you use this property - which incidentally also means that the apparent impedance of a ...

3

Practically we use capacitors when we require a large amount of charge to be flown within fractions of seconds.. Battery provides a nearly uniform voltage and effective in long use, but when it comes to discharge a large amount of charge in a fraction of second, battery is ineffective.. How ever by a building a capacitor with large capacitance we store a ...

2

I've to make an electronic circuit 'RC' and the relation between current and tension between two nodes must be fulfilled by a capacitor 'C' (it integrates the current; see the relation in the WP). I can use a battery with a constant tension to power the circuit ($V_{in}$in the second image) but not to model that relation.

0

I might be able to answer your question in the context of linear response theory: Response function: the power series expansion of the applied field generated by a weak external perturbation. Mathematically speaking, we can relate the average value of an observable $X$_i to the response function $\chi$ via \begin{align} \langle X_i(t)\rangle=\int_0^t dt'' ...

0

Its the first one. This is exactly what the "dagger" does. It transposes the spinor, converting it from a column spinor to a row spinor, and takes every entry to its complex conjugate, i.e:  \psi=\begin{pmatrix}\psi_L\\\psi_R\end{pmatrix} \xrightarrow{\dagger} \begin{pmatrix}(\psi^T_L)^* (\psi^T_R)^*\end{pmatrix} = \begin{pmatrix}\psi_L^\dagger ...

0

Sure we can rigorously define force: It's a number extrinsic to a mass that allows us to calculate the mass's acceleration given also the numbers assigned to its intrinsic physical properties. We only require the measurement of force to give us a number that correctly predicts the measured acceleration of the mass. If it does this, then the measurement is ...

0

I hope not to be boring with the following sentences. There are two more practicable characteristics for masses and velocities. First is the momentum $p = mv$, second is the energy $E = 1/2 m v^2$. Both are conserved values for a closed system and for both one has not to care about the relative speed of an observer (with the exception that we talk about non ...

0

There are several definitions of nonlinear and each can be somewhat dependent on context. In your question, I would imagine one could say the perturbation was nonlinear if there were higher order terms altering the "shape" of the metric. You could also argue that the perturbations were nonlinear if they made it so the metric could not be expanded in the ...

2

When you say If something goes outside, then it will decrease inside! what you assume is exactly a conservation law. It may seem trivial, but it is not necessarily. Consider the population of a city, for example. At one point in time, you measure how many people are within the city borders; let's call this number $N_0$. Then, you observe all city ...

2

When we say something is conserved or that there is a conservation law for a given thing, we mean that the quantity of it does not change. You neither lose nor gain any of that thing. More specifically, conservation can come in two flavours. Something can be globally conserved. This means that the total amount of that something in the universe does not ...

1

It has a very simple yet important meaning.It simply means that the quantity that you are observing will always stay the same,even if that means that it gets transferred to another form or convert to another medium.You can not simply create more "stuff" of that quantity and you can not destroy it.It can not be created from nothing and it can not just be ...

Top 50 recent answers are included