2ใคใฎ็ฉไฝใ่ก็ชใใฆไธไฝๅใใใใฟใผใณ๏ผ็ฒๅใใใฃใคใใปๅฐ่ปใ้ฃ็ตใใ ใชใฉ๏ผใใใใฏๅ็บไฟๆฐ \(e = 0\) ใฎๅฎๅ จ้ๅผพๆง่ก็ชใงใใ่ก็ชๅพใฏ2็ฉไฝใๅใ้ๅบฆใงๅใใฎใงใๆช็ฅๆฐใฏ1ใคใ ใ๏ผไธไฝใซใชใฃใ้ๅบฆ \(V\)๏ผใ
้ๅ้ไฟๅญใ ใใง่งฃใใใฎใ็นๅพดใใจใใซใฎใผใฎไธ้จใฏ็ฑใป้ณใปๅคๅฝขใซๅคใใฃใฆๅคฑใใใพใใ
(1) ไธไฝใจใชใฃใๅพใฎๅ
ฑ้ใฎ้ใ \(V\)ใ
(2) ่ก็ชไธญใซ็ฉไฝใๅใใๅ็ฉ๏ผ้ๅ้ใฎๅคๅใซ็ญใใ๏ผใ
ใ่ก็ชไธญใซ A ใ B ใใๅใใๅ็ฉใใจใ่ก็ชไธญใซ B ใ A ใใๅใใๅ็ฉใใฏๅคงใใใ็ญใใๅใใ้๏ผไฝ็จๅไฝ็จ๏ผใๅ้กๆใใฉใกใใฎ็ฉไฝใฎๅ็ฉใ่ใใฆใใใๅฟ ใ็ขบ่ชใใใ