Magnetic energy density

Definition

Magnetic energy density is the amount of energy stored in a magnetic field per unit volume. It is mathematically expressed as $u_B = \frac{B^2}{2\mu}$, where $B$ is the magnetic flux density and $\mu$ is the permeability of the medium.

5 Must Know Facts For Your Next Test

1. Magnetic energy density is measured in joules per cubic meter (J/m³).
2. It depends on both the strength of the magnetic field ($B$) and the properties of the medium through which it passes.
3. In a vacuum, permeability ($\mu_0$) has a constant value of approximately $4\pi \times 10^{-7} \text{H/m}$.
4. For materials with relative permeability ($\mu_r$), total permeability is given by $\mu = \mu_0 \mu_r$.
5. Magnetic energy density plays a crucial role in inductors and transformers, where energy storage and transfer are essential.

Review Questions

• What is the formula for calculating magnetic energy density?
• How does magnetic energy density change with an increase in magnetic flux density?
• Why is permeability important in determining magnetic energy density?

Related terms

Magnetic Flux Density: A measure of the strength and concentration of a magnetic field over an area, denoted by $B$, and measured in teslas (T).

Permeability: A property of a material that describes how easily a magnetic field can pass through it. It includes both absolute permeability ($\mu_0$) and relative permeability ($\mu_r$).

Inductor: A passive electrical component that stores energy in its magnetic field when electric current flows through it.