A convex mirror of focal length 20cm produces a magnification 1/2times of an object of size 8cm Find the - Physics - Ray Optics And Optical Instruments

Question

A convex mirror of focal length 20cm produces a magnification
1/2times of an object of size 8cm Find the change in size of the
image if the focal length of the mirror increases to 40cm?

Vara · Accepted Answer

Mirror equation:1f=1u+1vCase I:Magnification,m=-vu12=-vuu=-2vHence,1-20=1-2v+1v1-20=12vv=-10 cmu=-2×-10=20 cmhiho=-vuhi=--1020×8=4 cmCase II:1-40=120+1v1v=-140-120     =-340v=-13
3 cmhiho=-vuhi=--13 320×8=5
32 cmChange in size of the image=5
32 - 4=1 32 cm

A convex mirror of focal length 20cm produces a magnification 1/2times of an object of size 8cm. Find the change in size of the image if the focal length of the mirror increases to 40cm?