Thread: Grade 10 Optics question - Converging Mirrors

I am having serious trouble with this question and I'm hoping to get some assistance with it. The question goes as follows:

Suppose a lens with a focal length of 10.0cm produces an inverted image half the size of a 4.0cm object. How far apart are the object and image? Show all your work.

Any help is appreciated.

Originally Posted by ringelos

I am having serious trouble with this question and I'm hoping to get some assistance with it. The question goes as follows:

Suppose a lens with a focal length of 10.0cm produces an inverted image half the size of a 4.0cm object. How far apart are the object and image? Show all your work.

Any help is appreciated.

What answer did you come up with, and how did you try and figure it out?

If you haven't even tried, we won't do your homework for you (See homework topic)

You should have a formula for magnification in your optics chapter. Type it out and say what each variable means.

You should also be able to tell if this is a convex or concave lens. How?

m = hi/ho = -di/do
m= magnification (what we're looking for)
hi=image height
ho=object height
di=image distance
do=object distance

From what I can tell, we have a hi=2 and a ho=4 and a focal length that doesnt fit into the equation.
Is this correct?

So m= -2/4 = -di/do
m= -0.5

If I am correct we now have magnification - now what?
Do we multiply our focal length by 0.5 to get a value, then add said value to our focal length?

So, 10x-0.5 = -5, 10-5 = 5