Question

where will the image of an object placed at 6 CM in front of a concave mirror of focal length 12 CM be formed.Draw a ray diagram for this situation to justify your answer.

diagram is not important just need the image distance

Answer 1

1/v +1/u=1/f
1/v=1/f-1/u
=-1/12+1/6
=-1+2/12
=1/12
V=12

Answer 2

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Concave mirror case :-

So , now writing values by using sign convention .

u = ( object distance ) = -6 cm
f = ( focal length ) = -12 cm

Now , by using mirror firmulae ,
we get ,

1 / v + 1 / u = 1 / f

=> 1 / v - 1 / 6 = ( -1 ) / 12
=> 1 / v = 1 / 6 - 1 / 12
=> 1 / v = 2 - 1 / 12
=> 1 / v = 1 / 12
=> v = 12 cm

Here the image distance ( v ) is 12 cm .
It is in positive which indicates that the image is virtual and erect and gets firmed behind tge mirror .

The object us placed between focus and principal axis . So , in such case , virtual image gets formed .


And also the magnification is +2 .

So , by these information , ray diagram will also get formed .


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