Tichifunga nezvemashoko anotevera pamusoro pekumhanya kwechiedza: Nhanho yechiedza chiri muchadenga chine refractive index ye1 i300Km/sec Nhanho yechiedza mumvura ine refractive index ye 1.3 i225Km/sec Kumhanya kwechiedza mudhayamondi ine refractive index ye 2.4 i125Km/sec  Fungidzira kumhanya kwechiedza mugirazi rine refractive index ye1,5
Kubva mumashoko anopiwa tinogona kuona kuti kumhanya kwechiedza kunowirirana nenzira yakatarisana neindekisi yokutsauka kwechinhu chacho. Tinogona kufungidzira kukurumidza kwechiedza chiri mugirazi sechikamu chechikamu chechiedza chisina chinhu chakapatsanurwa nechikamu chokuputsanya chechinhu chacho. Muchiitiko chegirazi iro raizova 300Km/1.5 = 200Km/sec.  Nhanho inofungidzirwa yechiedza mugirazi ichava inenge 200 Km/sec