Chapter 13: Normal Incidence at an Interface

Animation 3

When a uniform plane wave impinges a flat material interface at a right angle (normal incidence of the wave), some of it is reflected back, and some of it is transmitted. This generates (1) a mixed wave in region 1 (the region in which the incident wave originates), and (2) a traveling wave in region 2 (the region beyond the material interface).

If the interface is at position x = 0, we calculate the reflection coefficient as

and the transmission coefficient as

Observe the reflected and transmitted pulses for two different ratios of the intrinsic impedances η 1 and η 2 :