Question

how far should an object be placed from a convex lens of focal length 20cm to obtain its image at a distance of 30cm from here from the lens what will be the height of the image if the object is 6 CM tall​

Answer 1

u=?

f=+20 cm

v=-30 cm

by mirror formula

1/v-1/u=1/f

-1/30-1/u=1/20

-1/30-1/20=1/u

-2-3/60=1/u

-5/60=1/u

u=-60/5=-12 cm

m=h'/h=+v/u

h'=v/u*h=-30*6/-12=15 cm

hope its the solution