A spherical refrativng suurface of denser medium `(mu=1.5)` is placed in a rarer medium `(mu=1.3)` .for an object lying in rarer medium at 20 cm from the surface,the virtual image is formed at 60 cm in rarer medium.find out the radius fo cruvature of the surface.

Explanation

`u=-10cm`
`v=60cm`
[ `:.` Lens forms the virtual image in rarer medium]
`u_(2)=1.5," "mu_(1)=1.3`
For the object in rarer medium
`-(mu_(1))/u+(mu_(2))/v=(mu_(2)-mu_(1))/R`
`-1.3/(-20)+1.5/(-60)=(1.5-1.3)/R`
`1.3/20-1.5/60=0.2/R`
`(3.9-1.5)/60=0.2/R`
`2.4/60=0.2/R`
`R=(60xx0.2)/2.4=5cm`
A sth valueof R is positive so it si a convex refracting surface.