# Wave Pattern Interference

### Nodal Line and Anti-nodal Line

1. An anti-node is a point of maximum amplitude where constructive interference occurs. Whereas a node is point of minimum amplitude where destructive interference occurs.
2. The anti-nodal line joins all anti-node points. The nodal line joins all node points.

#### Formula for Interference

$λ= ax D$ λ = Wavelength
a = Distance between the two wave sources
x = Distance between two successive anti-node lines or node lines
D = Distance from the wave sources to the plane where x is measured.