# Template:Incident plane wave in cylindrical coordinates

The incident potential is a wave of amplitude $\displaystyle{ A }$ in displacement travelling in the positive $\displaystyle{ x }$-direction. The incident potential can therefore be written as
$\displaystyle{ \phi^{\mathrm{I}} =e^{k_{0}x}\phi_{0}\left( z\right) =\sum\limits_{n=-\infty}^{\infty} I_{n}(k_{0}r)\phi_{0}\left(z\right) e^{i n \theta} }$