A paperweight in the form of a hemisphere of radius 3.0 cm is used to hold down a printed page. An observer looks at the page vertically through the paperweight. At what height above the page will the printed letters near the centre appear to the observer ?

Answer

(i) No shift is observed (ii) `1 cm`

Explanation

(i) For `AB` face `AB(1)/(v)+(1)/(u)=(2)/(R) R_(AB)=infty`
`(1)/(v)=-(1)/(u) |v|=|u|`
For spherical surface
`(n_(2))/(v)-(n_(1))/(u)=(n_(2)-n_(1))/(R)`
`(1)/(v)-(3/2)/(-3)=(1-(3)/(2))/(-3)` ltb rgt `v=-3`
So no shift

(ii)
`D_(app)=d_(actual)//n_(relative)=(3)/(3//2)=2 cm`
so shift `=3-2=1 cm` upward