Question

please give answer this question.......? ​

Answer 1

Answer:

40 cm

Explanation:

Given,

Focal length, f=−30 cm if u=−x

real ⇒ same side ⇒v=−ve

Magnification, m=uv⇒v=m×u=3×(−x)=−3x

From mirror formula, f1=v1+u1

We get −301=−3x1+−x1⇒301=3x1+3

⇒43x=3⇒x=40 cm

So object should be placed at 40 cm to the mirror

Answer 2

Answer:

f=-30cm

Let the object be object size be h then image size will be 2h

Note:Please remember that real image is always inverted

Now 2h/h= -v/u

-2=-v/u

v/u= 2

So v/u= 2

v=2u => v= 2u______i

1/f = 1/v + 1/u

1/f=1/2u + 1/u

1/-30=3/2u

-90=2u

u=-45

So, from i, we get v=2x-45

V= -90

And the distance of object from image or distance of image from the object = -90+45=-45cm