Question

A 2.90-cm-high object is situated 11.6 cm in front of a concave mirror that has a radius of curvature of 11.2 cm. Calculate (a) the location and (b) the height of the image.

Answer 1

Note that      
      
1/f = 1/do + 1/di      
      
where      
      
f = focal length = r/2 = 11.2 cm/2 =     5.6   cm
do = object distance =    11.6   cm
di = image distance      
      
Thus, solving for di,      
      
di =    10.8   cm, in front of the mirror   [ANSWER, PART A]
      
Thus, the magnification, m = -di/do,      
      
m =    -0.933333333  
      
Thus, as      
hi =    2.9   cm
      
And hf = m * hi, then      
      
hf =    -2.71   cm   [or, 2.71 cm INVERTED, ANSWER TO PART B]