Why Is My Calculation of Lens Object Distance Incorrect?

[luap12]

1.An object is placed to the left of a lens, and a real image is formed to the right of the lens. The image is inverted relative to the object and is one-half the size of the object. The distance between the object and the image is 102.0 cm.

(a1) How far from the lens is the object?



2.m=-(d_i/d_o)



3. with the equation above I thought it was just -1/2=120/d_o and solving for d_o gives -204 cm, but this answer is wrong, and so is 204. I know that m is negative because the image is inverted. Not sure if my logic is right or not, we haven't covered this yet in class but it is still on the homework.

 

[Gear300]

M = -q/p, in which q is the distance from the lens to the image and p is the distance from the lens to the object. The 102cm given is the distance between the object and image.

 

[luap12]

That worked, thanks. I had the wrong idea of what the terms actually meant.