Example: Long solonoid (see Figs. 9-6 and 9-7) It is very long so that the end effects will negligible Choose a cylindrical coordinates Figure 9-7 Components of B at P, in cylindrical coordinatesExample: Long Solonoid (see Figs. 9-6 and 9-7） It is very long so that the end effects will negligible. Choose a cylindrical coordinates