Question

The image of the object formed by a mirror is real,inverted and is of magnification -1.If the image is at the distance of 30 cm from the mirror,where is the object placed?find the position of the image if the object is now moved 20 cm towards the mirror what is the nature of the image obtained? Please justify you answer with the help of ray diagram

Answer 1

you can get your answer

in this pic.

i hope you understand well.

Answer 2

Answer: The image is virtual.

Explanation:

Given that,

Magnification m = -1

Distance of the image v= -30 cm

We know that,

The magnification is

$m = -\dfrac{v}{u}$

$-1 = -\dfrac{-30}{u}$

$u = -30 cm$

The object is placed at 30 cm from the mirror.

Using mirror's formula

The focal length is

$\dfrac{1}{f}=\dfrac{1}{v}+\dfrac{1}{u}$

$\dfrac{1}{f} = \dfrac{1}{-30}+\dfrac{1}{-30}$

$f = -15 cm$

If the object is moved 20 cm towards the mirror then,

u = -10 cm

Now, the distance of the image is

$\dfrac{1}{-15}=\dfrac{1}{v}+\dfrac{1}{-10}$

$\dfrac{1}{v}=\dfrac{1}{-15}+\dfrac{1}{10}$

$v = 30$

So, the image is formed behind the mirror.

Hence, The image is virtual.