An object is placed 21cm in front of a concave mirror of radius of curvature 20cm. A glass slab of thickness?

3cm and refractive index 1.5 is placed close to the mirror in the space between the object and the mirror. Find the position of the final image formed. The distance of the nearer surface of the slab from the mirror is 10cm.





Please tell all the steps. Thanks in advance.An object is placed 21cm in front of a concave mirror of radius of curvature 20cm. A glass slab of thickness?
the slab just makes your optical path bigger by (n-1)*d (d is the thickness) so 1.5cm in this case (1.5-1)*3





so your optical distance to the mirror is not 21cm but instead 22.5cm 21+1.5.


the focal distance of a concave mirror is positive so f=R/2=10cm





so your calculation goes very simply





1/si+1/22.5=1/10





si=10*22.5/(22.5-10)





si=18cm





now remember that this is the optical distance not the distance it self





remember the glass is actually between cm 10 and 13 from the mirror


First you realise that this distance is bigger then the 10 cm so it migth be on the other side of the glass lets try cheking this out by subtracting the total optical path introduced by the slab





18-1.5=16.5cm it's the actual distance from the mirror of of your image





just a heads up 3 things





first I don't consider any reflection in the glass,





second the glass hear is plane so no lens effect in it,





third but not last if anyone would ask you the magnification you would have to use the optical distances





m=-18/22.5


something inverted and less then one