! A lensball is a polished spherical ball of radius $`R=5 cm`$, made of glass of refractive
! A lensball is a polished spherical ball of radius $`R=5 cm`$, made of glass of refractive
index value $`n_{glass}=1.5`$. The cathedral is 90 meters high, and you stand with the lensball
! index value $`n_{glass}=1.5`$. The cathedral is 90 meters high, and you stand with the lensball
400 meters from the cathedral. You look at the cathedral through the lens, your eye being at 20 cm
! 400 meters from the cathedral. You look at the cathedral through the lens, your eye being at 20 cm
from the center of the lens. What would you expect to see?
! from the center of the lens. What would you expect to see?
!
!
! * _The resolution time is the typical expected time to be allocated to this problem if it was part of an examen for an optics certificate_.
! * _The resolution time is the typical expected time to be allocated to this problem if it was part
! of an examen for an optics certificate_.
!
!
! * _The discovery time is the expected time you require to prepare this challenge if you don't have practice. However, this is just an indication, take as much time as you need. The time to question yourself serenely about how to handle the problem, about the method of resolution and its validity, about some possible approximations if they can be justified, and the time you need to check the equations if you have not previously memorised them and to perfom the calculation, are important._
! * _The discovery time is the expected time you require to prepare this challenge if you don't
! have practice. However, this is just an indication, take as much time as you need. The time to question yourself serenely about how to handle the problem, about the method of resolution and its validity, about some possible approximations if they can be justified, and the time you need to check the equations if you have not previously memorised them and to perfom the calculation, are important._
