Question

the image of an 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 placedfind the position of the image in the object is no more 20 CM towards the mirror what is the nature of the image obtained justify your answer with the help of ray diagram

Answer 1

Yes an image formed by the bottom half

since it is still a mirror and the light will be focused in the same place where the full mirror would focus the light

you can apply the ray diagram to the bottom half the mirror to get the image position

the focal length of the mirror doesn't change and the brightness of the image decreases since amount of light forming the image is less

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.