Question

a convex lens has focal length 20cm. Atwhat distance from the lens should the object be placed so that the image is formed 40cm on the other side of the mirror ​. find nature of the image formed.

Answer 1

Given that, a convex lens has focal length 20 cm and image formed is of 40 cm on the other side of the mirror.

We have to find the object distance from the lens and nature of the image formed.

From above data we have; Focal length (f) of convex lens is 20 cm and image distance (v) is 40 cm.

Using Lens formula:

1/f = 1/v - 1/u

Substitute the known values,

→ 1/20 = 1/40 - 1/u

→ 1/u = 1/40 - 1/20

→ 1/u = (1 - 2)/40

→ 1/u = -1/40

→ u = -40

(Image formed is real.)

Therefore, the object distance from the lens is 40 cm.

Now, using magnification formula:

m = v/u

Substitute the values,

→ m = 40/(-40)

→ m = -1

As, the image distance and object distance from the lens is same; means the object is placed at C due to this image is also formed at C. Also, the height of image and object are same.

Answer 2

Explanation:

♻️ QUESTIONS ♻️

a convex lens has focal length 20cm. Atwhat distance from the lens should the object be placed so that the image is formed 40cm on the other side of the mirror . find nature of the image formed.

♻️ANSWER♻️

✍️-1

♻️To find♻️

nature of the image formed.

♻️ SOLUTION ♻️

f=20cm

v=40cm

u=?

according to lens equations.

$\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$

1/u=1/v-1/f=1/40-1/20

1/u=1-2/40=-1/40

u=-40cm

LENS OBJECT SHOULD BE PLACED 40 CM FROM THE LENS LENS IMAGE FORMED ON OTHER SIDE IT IS REAL.

Now.

magnification given is

m=v/u=40/-40=-1

m=h1/h0

h1=h0

✏️ HENCE ,IMAGE IS INVERTED AND SAME SIZE OF THE OBJECT✏️