内外球壳电势差为
U = ∫ (R1, R2) E.dr
= ∫ (R1, R2) Q / (4π ε0 r^2).dr
= Q / (4π ε0 ) * (1/R1 - 1/R2)
如果用电势叠加原理计算,则
内球壳电势 U1 = Q / (4π ε0 R1 ) + (- Q) / (4π ε0 R2 )
外球壳电势 U2 = Q / (4π ε0 R2 ) + (- Q) / (4π ε0 R2 )
内外球壳电势差
U = U1 - U2
= Q / (4π ε0 R1 ) - Q / (4π ε0 R2 )
两种计算方法结果一样。