Hello everyone, i don't think i'm understanidn ghits formula correctly. THe problem says: The wavelength of yellow sodium light in air is 589 nm. (a) What is its frequency? I found, 5.09E14 Hz (b) What is its wavelength in glass whose index of refraction is 1.74? ? nm OKay I'm using the equation; Wave Length of a Light = wave length of medium/index of medium But i'm not sure if i'm reading it right, it says: WaveLength1 = WaveLength2/n where n is the index of Refraction This equation relatse the wave lenght of light in any medium to its wavelength in vaccum. It tells us that the greater the index of refraction of a medium, the smaller the wavelength of light in that medium. So i said, WaveLength1 is the wave length of the medium, which is glass in my case. I said WaveLength2 is the wavelength of yellow sodium light in air is 589 nm. And n is of course 1.74; WaveLength = (589E-9)(1.74) = .000001, he wanted it in nm, so i said it was: 1000nm, which was wrong. ANy ideas on what I f'ed up on ? THanks@!