Thursday 17 March:

Target: Mirrors & Lenses:

The focal length (f) is positive  if parallel rays converge after hitting the mirror or lens otherwise  f  is negative.

1. An illuminated object is placed 0.60 meter from a lens whose focal length is +0.2. meters. 

The image is: 

a. Type of lens

b. Type of image

c. Dist of image to lens

d. Orientation

e. Magnification

1.

a. Converging lens (f = +0.2m)

b.  Real image (same side of lens as observer)

c.  1/ S_o + 1/S_i  = 1/f

1/.6  +  1/ S_i = 1/.2

1/ S_i = (3/.6) – (1/.6 ) à (3.33) 

S_i =  1/3.33 à .30m

 d.  Inverted real image

   e.  M =  S_{i /} S_o à (.30/.6) 

             M =   .5    or 1/2

2.    An illuminated object is placed 0.60 meter from a lens whose focal length is -0.2 meters.  The image is

a. Type of lens

b. Type of image

c. Dist of image to lens

d. Orientation

e. Magnification

a. Diverging lens ( f =  -0.2m)

b. Virtual image (opposite side of lens from observer)

c.  1/ S_o + 1/ S_i  = 1/f

1/.6  +  1/ S_i = -1/.2

1/ S_i = -(3/.6) – (1/.6 ) à (- 6.67) 

S_i = - 1/6.67 à  - 0.15m

d.  Upright

e.     M = - S_{i /} S_o à -(-.15/.6) 

        M =  .25