Answers from recently turned in homework

1.

a.  convex (since the f is +)
b.  di = 60 cm.  Use the lens equation:  1/f = 1/di + 1/do
c.  magnification = -2.  Use the magnification equation:  mag = -di/do
d.  real (since di is +)
e.  upside-down, since the mag is -

2.  Dimmer, but still in focus.  Fewer light rays make it, but their path is not changed.

3.  Place the object AT the focal length.

4.  Either within f, or between f and 2f