Find magnifications of image

Question

A 60 cm tall red rose is placed 40 cm from a large convex lens of focal length 20 cm.
Locate the position of the image by means of a ray diagram
Locate the position of the image by means of the mirror equation

Find the magnification of the image

What is the height of the image?

Answer 1

See GeoGebra ray diagram here:
http://www.wyzant.com/resources/files/264423/ray_diagram_for_rose

From ray diagram image is 40 cm from lens on opposite side as object.

Ref.: http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/lenscon.html

1/OD + 1/ID = 1/FL

1/40 + 1/ID = 1/20

1/ID = 2/40 - 1/40 = 1/40

ID = 40 cm on opposite side of lens as object

M = -ID/OD = -40/40 = -1,
where negative means image is inverted.
1 means same size as object.

So height of image is same as object, 60 cm.