Question

The image of an object formed by a mirror is real and inverted and is of magnification -1. If the inage is at the distance of 30cm from the mirror,where is the object placed? Find the position of the image if the object is now moved 20cm towards the mirror. What is the nature of the image obtained? Justify your answer with the help of ray diagram

Answer 1

1.the object is placed 30 cm away from mirror
2. The nature of image is real inverted and magnification -1

Answer 2

Answer:

+ 30 cm

Explanation:

Given :

Magnification = - 1

Image distance = 30 cm

We know

m = - v / u

- 1 = 30 / u

u = - 30 cm

Now we have ,

1 / f = 1 / v + 1 / u

1 /  f = 1 / - 30 - 1 / 30

f = - 15 cm

When object moved 20 cm

u' = - 30 + 20 = - 10 cm

We have f = - 15 cm

We have to find new image distance v'

Again ,

1 / f = 1 / v' + 1 / u'

- 1 / 15 = 1 / v' - 1 / 10

1 / v' = 1 / 30

v' = 30.

Nature of image as :

Virtual

Erect

Magnified.