Question

A convex lens forms an image of magnification -2 of the height of image is 6 cm, the height of object is​

Answer 1

Answer:

The height of the object is 3cm.

Explanation:

Given info: A convex lens forms an image of magnification -2 of the height of the image is 6cm.

To find: the height of object is ...

solution : magnification, m = -2 , negative sign indicates that image is real , inverted.

so  height of image,  = -6cm

we know, magnification is the ratio of the height of image to that of object.

∴ magnification, m = height of image/height of object = h^i/h^o

⇒ -2 = -6cm/height of object

⇒ height of object = 3 cm

therefore the height of object is 3cm.

Answer 2

Given:

A convex lens forms an image of magnification -2 and the height of image is 6 cm.

To find:

Object height?

Calculation:

• We know that the magnification of lens is equal to ratio of image height and object height.

• Now, since the image is real with magnification sign as negative, we will put the image height as -6 cm.

$\dfrac{h_{i}}{h_{o}} = magnification$

$\implies \dfrac{ - 6}{h_{o}} = - 2$

$\implies h_{o} = \dfrac{ - 6}{ - 2}$

$\implies h_{o} =3 \: cm$

So, object height is 3 cm.