A pin is placed 40cm away from a convex lens of focal lenght 20cm. Determine the maginification of the pin formed by the lens.

m = 40/20 = 2

am i right with this?

You have f, and do

1/do + 1/di = 1/f

di=dodf/(do+df)=800/60

M= do/di

check my thinking.

No, the calculation you provided is incorrect. The magnification of an image formed by a lens can be determined using the formula:

magnification (m) = -image distance (di) / object distance (do)

In this case, the object distance (do) is 40 cm and the focal length (f) is 20 cm.

Using the lens formula: 1/f = 1/do + 1/di

Solving for the image distance (di):

1/20 = 1/40 + 1/di
(di - 40)/(di*40) = 1/40
di - 40 = di/40
di - di/40 = 40
(40di - di)/40 = 40
39di/40 = 40
39di = 40 * 40
di = 1600/39

Now that we have the image distance (di), we can substitute it into the magnification formula:

m = -di / do
m = -(1600/39) / 40
m ≈ -1.03

Therefore, the magnification of the pin formed by the lens is approximately -1.03. Note that the negative sign indicates that the image is inverted.

Yes, you are correct! The magnification (m) of an object formed by a lens can be determined using the formula:

magnification (m) = distance of image from lens / distance of object from lens

In this case, the object (the pin) is placed 40 cm away from the convex lens. The focal length of the lens is given as 20 cm.

Therefore, the magnification (m) is:

magnification (m) = 40 cm / 20 cm

magnification (m) = 2

So, the magnification of the pin formed by the lens is 2, which means the image formed by the lens is twice the size of the object.