ok so this was in my end of unit test today and i have been stressing as to what i should have done, so as it's not really homework you could always just tell me the answer pretty basic stuff, a ray of light is incident from a substance upon the surface of another substance with n=1. i can't remember the exact refractive index of the first material but it was about 1.4 or something, hmm. anyway, i worked out the incident abgle to be 47 degrees and to find the refractive angle used sin incident angle x n1 = sin refractive angle x n2 seeing as n2 = 1 then you get sin refracted angle = sin incident angle x n1 which ended up being about 1.09 or something, ok, a sine>1 ??? well i just pretended it was 1 and so worked out the refracted angle to be total, ie 90 degrees. was this the right thing to do? was this some measurment discrepancy i was supposed to disregard? help, i don't want to wait a month for results to understand this problem!