Question

An opaque cylindrical tank with an open top has a diameter of 2.80 m and is completely filled with water. When the afternoon Sun reaches an angle of 31.2

Answer 1

Here is what I solved before, please modify the figures as per your question. Please let me know if you have further questions. Ifthis helps then kindly rate 5-stars.

an opaque cylindrical tank with an open top has a diameter of3.00 m and is completely filled with water. when theafternoon Sun reaches an angle of 28.0 degrees above the horizon,sunlight ceases to illuminate any part of the bottom of thetank. how deep is the tank?

When light passes from one medium to another it bends due torefraction.

So your question can be picturised as follows,

when the afternoon Sun reaches an angle of 28.0 degrees abovethe horizon, sunlight ceases to illuminate any part of the bottomof the tank , the bottom will remain dark

Here i is the angle of incidence and r is the angle ofrefraction.

i =90-28 =62 degrees.

Now we can apply snells law,

n₁sin i = n₂sin r . {n₁=1isthe refractive index of air and n₂=1.33 is that ofwater

sin r =sin 62/1.33 =0.66.   or   r=sin^-10.66