这是一份bath巴斯大学PH30079作业代写的成功案

$$
\mu_{\mathrm{dc}}=-\left(V_{\mathrm{s}}+V_{\mathrm{h}}+V_{\mathrm{c}}\right) \frac{B_{\mathrm{app}}}{\mu_{0}} .
$$
For field cooling, the magnetic field is trapped in the open hole, while surface currents shield the superconductor itself and the enclosed cavity from this field, which gives for the magnetic moment
$$
\mu_{\mathrm{fc}}=-\left(V_{\mathrm{s}}+V_{\mathrm{c}}\right) \frac{B_{\mathrm{app}}}{\mu_{0}} .
$$
Associated with the effective magnetic moment (5.16) there is an effective magnetization $M_{\text {eff }}$ defined by Eq. (5.5) in terms of the total volume $(5.15)$
$$
M_{\mathrm{eff}}=\frac{\mu_{\mathrm{eff}}}{V_{\mathrm{T}}}=\chi_{\mathrm{eff}} \frac{B_{\mathrm{app}}}{\mu_{0}} .
$$

PH30079 COURSE NOTES ：

A quantitative measure of the degree of granularity of a sample is its porosity $P$, which is defined by
$$
P=\left(1-\rho / \rho_{x^{-r a y}}\right),
$$
where the density $\rho$ of the sample is
$$
\rho=\frac{m}{V_{\mathrm{T}}}
$$
and the $x=r a y$ density is calculated from the expression
$$
\rho_{\mathrm{x}-\mathrm{ray}}=\frac{[\mathrm{MW}]}{V_{0} N_{\mathrm{s}}}
$$