Question

a concave mirror of focal length 12 cm is placed at a distance of 60 cm from a wall. how far from the wall an object be placed so that its sharp image formed by the mirror falls on the wall

Answer 1

Answer:

Here, f =-10cm; v =-35 cm (since the image is formed on the wall and distance between the wall and mirror is 35cm).

Image is beyond 2f so object has to be in between F and C.

Let the distance of the object from the wall be x. Therefore, the distance of the object from the wall = 21 cm.

Step-by-step explanation:

Here, f =-10cm; v =-35 cm (since the image is formed on the wall and distance between the wall and mirror is 35cm). Image is beyond 2f so object has to be in between F and C. Let the distance of the object from the wall be x. Therefore, the distance of the object from the wall = 21 cm.

Answer 2

Step-by-step explanation:

$\huge\bf\maltese{\underline{\pink{Answer}}}\maltese$

Here,

Focal Length = 12 cm.

Distance = 60 cm.

( Since, the image is formed on the wall and the distance between the wall and mirror is 35cm. )

[ And, the image is beyond 2f, so object has to be in between F & C ].

$\huge{\bf{\underline{\red{Solution}}}} →$

Let the distance of the object from the wall be x.

=> u = - ( 60 - x )

$=> \frac{1}{u} + \frac{1}{v} = \frac{1}{f}$

$=> \frac{1}{ - (60 - x)} + \frac{1}{ - 60} = \frac{1}{12}$

$=> \frac{1}{60 -x} + \frac{1}{60} = \frac{1}{12}$

$=> \frac{1}{60 - x} = \frac{6 - 2}{120}$

$=> 35 - x = 4$

$=> x = 8.7$

Therefore, the distance from the wall

= 3.5 cm.

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