R ′ =R/A = I/ E ⊥ A MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHXgaruavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaiqaciWacmGadaGadeaabaGaaqaaaOqaaiqadkfagaqbaiabg2da9maalyaabaGaamOuaaqaaiaadgeaaaGaeyypa0ZaaSaaaeaadaWcgaqaaiaadMeaaeaacaWGfbWaaSbaaSqaaiabgwQiEbqabaaaaaGcbaGaamyqaaaaaaa@3E5D@
unit: cd • lх -1 • m -2
NOTE – This quantity is particularly suitable for describing materials in sheet form.