Φ_{e} = L_{e} Δ Σ Δ Ω_{1} = L_{e} Δ Σ \frac{Δ σ}{R^{2}} = L_{e} Δ σ Δ Ω_{2}

${\Phi_e = L_e \Delta \Sigma \Delta \Omega_1 = L_e \Delta \Sigma \frac{\Delta \sigma}{R^2} = L_e \Delta \sigma \Delta \Omega_2}$

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