Question

Light usually refers to visible light, which is electromagnetic radiation that is visible to the human eye and is responsible for the sense of sight.Read para and answer
(i)A concave mirror produces 3 times magnified real image of an object at 10 cm in front of it.Where is image located
(ii)If a concave mirror has a focal length of 10 cm find the 2 positions where an object can be placed to give image twice height of object.
(iii)An object is placed at a distance of 12 cm from a cancave mirror The image formed is real and 4 times lapger than the object.Caliculate distance of image from the mirror.
please answer all questions with detailed explanations

Answer 1

1.  m = -3 = -v/u  =>  v = 3 u  = -30 cm    as u = - 10cm 

2. f = -10cm     
     v = 2u  =>  1/2u+ 1/u = -1/10    =>  u = - 15 cm    v= - 30 cm
     v = -2 u  =>  -1/2u +1/u = -1/10  =>  u = -5 cm

3.
       u = -12cm      m = -4 = - v/u      v = 4u = -48 cm
          -1/48 -1/12 = 1/f  =>  f = - 48/5 cm