Q. 233.6( 9 Votes )

# A 5 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 18 cm at a distance of 12 cm from it. Use lens formula to determine the position, size and nature to the image formed.

Answer :

According to the question;

Object distance = -12cm;

Image distance = v;

Focal length = 18cm;

By lens formula;

⇒ v = -36cm.

Therefore, image is formed at 36 cm in front of lens.

Now;

Height of object h_{1}= 5cm;

Magnification = =

Putting values of v and u

Magnification =

⇒

⇒

Height of image is 15 cm.

Thus, the image is virtual, enlarged, and erect and three times the size of object.

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An object is kept at a distance of 100 cm from each of the above lenses.

Calculate the

(a) image distance and

(b) magnification in each of two cases.

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