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NEET-XII-Physics

pp year:2018

with Solutions -
Qstn# 4 Prvs-QstnNext-Qstn
  • #4
    An object is placed at a distance of 40 cm
    from a concave mirror of focal length 15 cm.
    If the object is displaced through a distance
    of 20 cm towards the mirror, the displacement
    of the image will be:-
    (1) 30 cm away from the mirror
    (2) 36 cm away from the mirror
    (3) 30 cm towards the mirror
    (4) 36 cm towards the mirror
    digAnsr:   2
    Ans : (2)
    Sol. (i)
    object
    40 cm
    f = 15 cm
    0
     
    = =
      +
    1
    uf ( 40)( 15)
    v
    u f 40 15
    = = 
    
    600
    24cm
    25
    (ii)
    /////////////////////////////
    object
    20 cm
    f = 15 cm
     
    = =
      +
    2
    uf ( 20) ( 15)
    v
    u f 20 15
    = -60 cm
    Displacement of image = v2 - v1 = -36 cm
    = 36 cm away from the mirror.