# isaac physics help with optics

Taking the refractive index of the prisms as 1.5, find the smallest angle to the horizontal in degrees at which light can be incident on the first prism and fail to emerge from the periscope. Assume that the rays do not hit the edge of any of the 'tube' sections of the periscope at any point.im really stuck on this question and would love some help
Really hard to answer this without a diagram or more information. Perhaps a link?
Original post by Radioactivedecay
Really hard to answer this without a diagram or more information. Perhaps a link?

https://isaacphysics.org/questions/ch_d_p2?board=physicsskills_book_ch_dd
is on isaac physics on optics topic with the question marked periscope part b
Original post by Gamelon
Taking the refractive index of the prisms as 1.5, find the smallest angle to the horizontal in degrees at which light can be incident on the first prism and fail to emerge from the periscope. Assume that the rays do not hit the edge of any of the 'tube' sections of the periscope at any point.im really stuck on this question and would love some help

The answer is sin(90) / sin(45) = 1.41