Size of image of an object by a mirror having a focal length of `20 cm` is observed to be reduced to `1/3rd` of the size ? At what distance the object has been placed from the mirror ? What is the nature of the image and the mirror ?

Explanation

To solve the problem, we will use the mirror formula and the magnification formula. The given information is:

- Focal length of the mirror (F) = 20 cm
- Size of the image is reduced to 1/3rd of the size of the object, which means the magnification (M) = -1/3 (the negative sign indicates that the image is inverted).

### Step 1: Use the magnification formula
The magnification (M) is given by the formula:
\[ M = \frac{h'}{h} = -\frac{V}{U} \]
...