Question

If magnification of -1 is to be obtained by using a converging lens of focal length 12 cm , then the object should be placed :

Answer 1

Answer:

40 cm is your answer

Explanation:

..................

Answer 2

Given: A magnification of -1 is to be obtained by using a converging lens of focal length 12 cm.​  

To find: The position of the object.  

Solution:  

• The magnifying power of a magnifying glass is given by the formula,

        $M = 1 + \frac{D}{f}$

• Here, M is the magnification of the glass, D is the least distance of distinct vision and f is the focal length of the glass.
• On replacing the terms with the values given in the question,

        $-1 = 1 + \frac{D}{12cm}$

• On rearranging and solving further, the value of D is found to be,

        $D = -24 cm$

• The object distance is negative because it is always placed to the left of the lens.

Therefore, the position of the object is 24 cm to the left of the lens.