Question

В соленоиде сечением S=5см^2 создан магнитный поток Ф=20 мкВб. Определить объемную плотность w энергии магнитного поля соленоида. Сердечник отсутствует. Магнитное поле во всем объеме соленоида считать однородным.

Answer 1

Вот основная формула:
ω = $\frac{W}{V} = \frac{B^2}{2*4*3.14}$ - 4п - магнитная постоянная.
Ф = BS - магнитный поток. 
Отсюда B = Ф/S
Подставляешь и считаешь..
У меня вышло 0,0637

Answer 2

Calculation of Volume Energy Density of Magnetic Field in a Solenoid

To determine the volume energy density of the magnetic field in a solenoid, we need to use the formula:

w = (1/2)μ₀B²

where: - w is the volume energy density of the magnetic field, - μ₀ is the permeability of free space (constant), - B is the magnetic field strength.

In this case, the magnetic flux Φ is given as 20 μWb and the cross-sectional area S is given as 5 cm².

To find the magnetic field strength B, we can use the formula:

Φ = BS

where: - Φ is the magnetic flux, - B is the magnetic field strength, - S is the cross-sectional area.

Rearranging the formula, we have:

B = Φ / S

Substituting the given values, we get:

B = (20 μWb) / (5 cm²)

Converting the units to SI units, we have:

B = (20 × 10^(-6) Wb) / (5 × 10^(-4) m²)

Simplifying the expression, we get:

B = 0.04 T

Now, we can calculate the volume energy density w using the formula mentioned earlier:

w = (1/2)μ₀B²

Substituting the values, we have:

w = (1/2) × (4π × 10^(-7) T·m/A) × (0.04 T)²

Simplifying the expression, we get:

w = 1.6 × 10^(-7) J/m³

Therefore, the volume energy density of the magnetic field in the solenoid is 1.6 × 10^(-7) J/m³.