Question

the focal length of a convex lens is 10cm. Where should an object be placed in front of this lens to obtain a real, inverted and same sized image

PLS PLS HELP​

Answer 1

convex lens = to concave mirror ,so radius of curvature is double of its focal length

right answer is 20 cm

Answer 2

Answer:

At 2F₁

Explanation:

If you have read all the ray diagrams related to spherical mirrors and spherical lens, you will no longer suffer from such an easy question. Its really simple if you have thoroughly studied the ray diagrams and their rules about the spherical diagrams.

let's recall each and every ray diagram of spherical lens and their positions formed images.

• Position of the object ⇒ Position of the image ⇒ Relative size of the image ⇒ Nature of the image

1. At infinity ⇒ At focus F₁ ⇒ Highly diminished, point-sized ⇒ Real and inverted
2. Beyond 2F₁ ⇒ Between F₂ and 2F₂ ⇒ Diminished ⇒ Real and inverted
3. At 2F₁ ⇒ At 2F₂ ⇒ Same size ⇒ Real and inverted
4. Between F₁ and 2F₁ ⇒ Beyond 2F₂ ⇒ Enlarged ⇒ Real and inverted
5. At focus F₁ ⇒ At infinity ⇒ Infinitely large or highly enlarged ⇒ real and inverted
6. Between focus F₁ and optical centre O ⇒ On the same side of the lens as that of the object ⇒ Enlarged ⇒ Virtual and erect

From the above table is conformed that, the object should be placed at 2F₁ or at focus to obtain a real, inverted and same sized image.

There is no need of cramming the whole table as long as you know how to draw each and every ray diagram and the understanding of each and every topic in this chapter is must.