Placement of an object and magnification

[Violagirl]

Homework Statement

An object is 1 m from a screen. At what points may a 0.05-m focal length lens be placed so as to produce a sharp image on the screen? What are the corresponding magnifications?

Homework Equations

Lens maker equation:

1/s + 1/s' = 1/f

Magnification equation:

m = -s'/s = -f/s

The Attempt at a Solution

For the first question:

1/s' = 1/f -1/s = 1/0.05 m_-1 = -.95 m.

1 m - .95 m = 0.05 m away from the screen.

Magnification:

m = -0.05 m / 1 m = -0.05

Is this right?

 

[Basic_Physics]

Use the fact that the sum of the object and image distances is 100 cm.