Concepts

Class 10
Chapter 10 Class 10 - Light - Reflection and Refraction

We saw that, image formed by convex lens is

 Position of the object Position of the image Relative size of the image Nature of the image At infinity At focus F 2 Highly diminished,  point-sized Real and inverted Beyond 2F 1 Between F 2 and 2F 2 Diminished Real and inverted At 2F 1 At 2F 2 Same Size Real and inverted Between F 1 and 2F 1 Beyond 2F 2 Enlarged Real and inverted At focus F 1 At infinity Infinitely large or highly enlarged Real and inverted Between focus F 1 and optical Center O On the same side of the lens as the object Enlarged Virtual  and erect

Now, let us see where convex lens is used

### Convex lens is used as

• It is used as Magnifying Glass
• It is used to Make Microscope
• It is used in spectacles to correct the vision. It cures defects called hypermetropia (far sightedness) where patients can't see objects closer to them

## Uses of Concave Lens

We saw that, image formed by concave lens is

 Position of the object Position of the image Relative size of the image Nature of the image At infinity At focus F 1 Highly diminished, Point - Sized Virtual and erect Between infinity and optical centre O of the lens Between focus F 1 and optical centre O Diminished Virtual and erect

Now, let us see where concave lens is used

### Concave lens is used as

• It is used as a spy hole in doors (where we can see visitor from a small opening)
• It is used in spectacles to correct the vision. It cures defects called myopia (near sightedness) where patients can't see objects far away
• They are used in camera to focus on a single object, Hence we get a clearer picture
• It is used in Flashlights. Concave lenses are used in flashlights to widen the beam produced by the bulb.