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  2. Standard formula for energy density of electromagnetic field

    physics.stackexchange.com/questions/562563/standard-formula-for-energy-density...

    The formula for energy density of electromagnetic field in electrodynamics is $$\frac{1}{8\pi} (\vec E\cdot\vec D+\vec B\cdot\vec H).$$ This formula appears in all general physics courses I looked at.

  3. Therefore we may consider energy stored per unit volume as H.dB integral over its time growth.Look, that this depends on how B has grown with H. In free space since there is no magnetization B=uoH and so energy density is B^2/2uo.

  4. Yes, $\epsilon \vec E \cdot \vec E$ is the electrostatic part of the energy density carried by the field. The energy density of the electromagnetic field also includes the magnetic term: $$ \rho_{E,B} = \frac{\epsilon}{2} |\vec E|^2 + \frac{1}{2\mu} |\vec B|^2 $$ and this formula is valid even for arbitrary time-dependent, variable ...

  5. What's the total Cosmic Microwave Background energy?

    physics.stackexchange.com/.../whats-the-total-cosmic-microwave-background-energy

    The energy density of the Cosmic Microwave Background (CMB) is $4.19 \times 10^{-14} J/m^3$. This value can be calculated from the CMB temperature being 2.728 K and

  6. What is Pressure Energy? - Physics Stack Exchange

    physics.stackexchange.com/questions/216342

    6. The pressure energy is the energy in/of a fluid due to the applied pressure (force per area). So if you have a static fluid in an enclosed container, the energy of the system is only due to the pressure; if the fluid is moving along a flow, then the energy of the system is the kinetic energy as well as the pressure.

  7. How to derive the energy density of a sound wave?

    physics.stackexchange.com/questions/711465/how-to-derive-the-energy-density-of...

    The total energy density is then given by. dEk dV + dEp dV = ρω2s20cos2(kx − ωt). d E k d V + d E p d V = ρ ω 2 s 0 2 cos 2 (k x − ω t). We may be interested in the mean energy density, in which case we integrate the energy density in time over one period and divide by one period. This process leads to.

  8. Negative energy density of a blackbody? - Physics Stack Exchange

    physics.stackexchange.com/questions/362032/negative-energy-density-of-a-blackbody

    3. 1 Answer. The sign comes from your expression dν = −c λ2 dλ d ν − c λ 2 d λ and it just means that frequency and wavelength are inversely proportional i.e. if you increase λ λ by dλ d λ then the frequency decreases i.e. the change in the frequency dν d ν is negative. If you're calculating the energy density over some range ...

  9. How to compute the self-energy of a sphere? Electrostatics

    physics.stackexchange.com/questions/606619/how-to-compute-the-self-energy-of-a...

    Self-energy of a uniformly charged, non-conducting sphere, using energy density formula (1 answer) Closed 3 years ago . Not just the formula, how to derive it as well, im lost in this topic any help would be great.

  10. Understanding Strain Energy Density - Physics Stack Exchange

    physics.stackexchange.com/questions/679327/understanding-strain-energy-density

    Sorted by: 1. For quasistatic reversible elasticity, conservation of energy can be written as, ∫ V˙udV = ∫ VbividV + ∫ StividS. Where u is the strain energy density, bi is the body force density, ti is the surface traction, and vi is the velocity. Conservation of linear and angular momentum, which for quasi-static processes are simply ...

  11. How energy curves spacetime? - Physics Stack Exchange

    physics.stackexchange.com/questions/70993

    The mass is energy, firstly., which is why it curves spacetime. . . The EinsteinHilbert action from which the EinsteinFieldEquation can be derived, are the true reason for why energy (and thus mass) curves spacetime. And it's not about "matter". It is about "mass". Contrary to propaganda spread by Primary School teachers, mass is not the amount ...