Question

image of an object formed by a mirror is real inverted and is of magnification -1 if the image is at the distance of 30cm from 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 nature of the image obtained

Answer 1

Answer:

The object is placed at the Center of Curvature.. If the object is moved 20 cm towards the mirror then the image will be behind the mirror , virtual , erect and enlarged

Step-by-step explanation:

Magnification is -1 only when object is at C

C=2f

Therefore f=15cm

Thus when pushed 20cm ahead object will be past the focus at 10cm

Thus between P & F image is always virtual erect enlarged

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.