use n= ?1/?2

If we assume that the refractive index (n) of quartz is stated with respect to air, we can argue as follows: refractive index is the ratio of the speed of light in air to the speed of light in quartz. Since wavelength is proportional to speed, the wavelength in a medium (in this case quartz) is inversely proportional to the refractive index of the material. So wavelength in quartz = 355/1.55 = 229nm The question tells us the speed of light in quartz, this enables us to determine the refractive index (n), and check whether the information given in the question is internally consistent. Assuming that the speed of light in vacuum (c) is not significantly different from that in air we can write: n = c/1.94*10^8 = 1.545, which, to 2pds,

If we assume that the refractive index (n) of quartz is stated with respect to air, we can argue as follows: refractive index is the ratio of the speed of light in air to the speed of light in quartz. Since wavelength is proportional to speed, the wavelength in a medium (in this case quartz) is inversely proportional to the refractive index of the material. So wavelength in quartz = 355/1.55 = 229nm The question tells us the speed of light in quartz, this enables us to determine the refractive index (n), and check whether the information given in the question is internally consistent. Assuming that the speed of light in vacuum (c) is not significantly different from that in air we can write: n = c/1.94*10^8 = 1.545, which, to 2pds,

1) a) angle of reflection = angle of incidence so your answer will be the same (47.5) b) use Snell's law to answer this part sin i /sin r = refractive index. angle of incidence = 90 - 47.5 = 42.5 sin r = sin 42.5/1.66 I'll let you do the calculator button pressing you can then easily calculate the angle between surface and ray. to answer Qs 2 and 3 you will need to do the same thing. have fun working them out. Actually you may want to check whether this is a trick question . The angle of incidence may well be over the critical angle (c)- in which case the refracted angle will be 90 so angle with glass is zero. 1/sin c = refractive index sin c = 1/1.66 c = sin ^-1 1/1.66) . Comes to about 37 degrees so it will reflect off!!