Question

A diverging lens with a focal length of -15 cm and a converging lens with a focal length of 15 cm have a common central axis. Their separation is 12 cm. An object of height 1.0 cm is 10 cm in front of the diverging lens, on the common central axis.

(a) Where does the lens combination produce the final image of the object (the one produced by the second, converging lens)?
in cm
(b) What is the height of that image?
in cm

(c) Is the image real or virtual?

virtua

lreal     

cannot tell from the given information

(d) Does the image have the same orientation as the object or is it inverted?

inverted

not inverted (erect)    

cannot tell from the given information

Answer 1

hI

So, two lenses, one divergent and the other convergent. The object for the convergent lens is the image of the divergent one.

First obtain image of divergent lens:

Now this image will be the object for the convergent lens:

\

b) Same idea as before

for the divergent lens:

which means not inverted and shorter than object.

For the convergent lens, this will be the height of the object:

From the signs then we conclude that this final image is real, not inverted, and shorter than original one.