Question

Constants SOLUTION Light rays that enter your eye are affected by the fluid that fills the eyeball, called the vitreous humor (Figure 1). When red light from a l = 633 nm helium-neon laser enters your eye, its wavelength drops to 474 nm. Use this information to calculate the index of refraction of the vitreous humor and the speed and frequency of light passing through it. SET UP AND SOLVE We don't need to sketch this problem because we're interested only in the index of refraction of a material and the speed of light in it, not in the path a particular ray follows. The index of refraction of air is very close to 1, so we assume that the wavelength of the laser light is the same in vacuum as in air. Then the wavelength in the material is given by: n= * = 633 nm = 1.34 which is about the same as for water. Then, to find the speed of light in the vitreous humor, we use n = c/v: 3.00x109 m/s = 2.24 x 108 m/s v=$ = 3.00x109 m/s 1.34 The frequency of the light is f=y= 2.24x10° m/s = 4.73 x 104 Hz f==474x10-m REFLECT Note that while the speed and wavelength have different values in air and in the vitreous humor, the frequency fo in air is the same as the frequency f in the vitreous humor (and the frequency in vacuum): fo = = 633x10-ºm 3.00 x 108 m/s != 4.73 x 1014 Hz 1014 Figure < 1 of 1 > This result confirms the general rule that when a light wave passes from one material into another, the frequency doesn't change. Lens Part A - Practice Problem: Cornea Vitreous humor Optic nerve The newest laser pointers emit light with a wavelength of lo = 594nm in air. What is the wavelength of this light in the vitreous humor of the eyeball? Express your answer to three significant figures and include appropriate units. CHÅR O O ? |

Answer 1

a)Given wavelength of air= 1, = 594nm=594x10 m refractive index of air=n, =1 Since frequency does not depend on material medium The wavelength of light of the eyeball is, (1)(594x10 1.34 = 4.432835821x10-7m -443x10m = 443nm