Question

If the image distance is 30cm from the mirror and magnification

is 1.5, the distance of the object is​

Answer 1

Explanation:

Given,

Focal length, f=−30 cm if u=−x

real ⇒ same side ⇒v=−ve

Magnification, m=

u

v

⇒v=m×u=3×(−x)=−3x

From mirror formula,

f

1

=

v

1

+

u

1

We get

−30

1

=

−3x

1

+

−x

1

⇒

30

1

=

3x

1+3

⇒

4

3x

=3⇒x=40 cm

So object should be placed at 40 cm to the mirror.

Answer 2

Given,

Image Distance (v) = 30 cm (positive)

Linear Magnification (m) = +1.5

Let the Object Distance be u,

m = -(v/u)

+1.5 = -(30/u)

+1.5 = -30/u

+1.5u = -30

u = -20 cm

The Object Distance is 20 cm from the mirror.

I hope this helps.