This document discusses different types of lenses, including convex and concave lenses. A convex lens is thicker at the center and thinner at the edges, forming an image that is real, inverted, and appears close to the lens. A concave lens is thicker at the edges and thinner at the center, forming an image that is virtual, erect, and appears far away. Examples of applications of convex and concave lenses include spectacles, telescopes, binoculars, flashlights, and spy holes. The document asks questions to test understanding of lens properties and applications.

1. Spherical Lens
B.Sc. B.Ed. Integrated

5. Types of lens.
• A concave lens is thicker
at the edges and
thinner at the center.
• A convex lens is thicker
at the center and
thinner at the edges.

6. Convex lens(converging lens)

8. Convex lens forms an image that is:
 Real
 Inverted
 the image is large and appears close to the lens.

9. Application
In the manufacturing of
• Spectacles
• telescope
• binoculars

10. what happen if we use
normal glass in microscope
instead of convex lens?

11. Question
• Convex lens
a)Shrinks the image
b)Magnifies the image.
c)Sharpens the image.
d)Inc. the contrast of the image.

12. What is
this?
What is
the use
of this?

13. They both are wearing specs that mean they
both having same eyesight problem. Is it so?

14. Concave lens(diverging lens)

16. Concave lens forms an image that is:
• Virtual
• Erect
• small and appears far away

17. Application
• Spectacles.
• Flashlight.
• Spy hole.

18. Questions
Eye can be corrected by using proper
a) Convex lens.
b) Concave lens.
c) Cylindrical lens.
d) Bifocal lens.

19. Can you name them?

20. Concave lens and also convex mirror
both are diverging. So are they same?
Can we called convex mirror as concave
lens ?

21. Similarity
Convex lens Concave lens
It converge parallel rays to a
focal point.
It converge parallel rays to a
focal point.

22. Difference

23. Specs are made up of concave or
convex lens? And why?

24. Question
• Diverging lens is
a)Convex lens
b)Convex mirror.
c) Concave lens
d)Concave mirror
• Those lens which feel
thicker in middle than at the
edges are
a) Convex lens
b) Convex mirror.
c) Concave lens
d) Concave mirror

25. RECAPITULATION
Today we studied about spherical lens i.e. curved
lens & these are of two types. Concave and convex
lens.
• Define converging lens
• Define diverging lens.
• Tabulate Difference between concave and convex
mirror.
• application of concave and convex lens.

26. HOME WORK
Take a convex lens or magnifying glass. Put it in the path of
sunrays. Place a sheet of paper as shown (Fig. 15.23). Adjust the
distance between the lens and the paper till you get a bright spot on
the paper. Hold the lens and the paper in this position for a few
minutes. Does the paper begin to burn?
Now replace the convex lens with a concave lens.

27. Questions.
 Do you see a bright spot on the paper this time,
too?
 Why are you not getting a bright spot this time?
 We have seen in the case of mirrors that for
different positions of the object the nature and size
of the image change. Is it true for lenses also?