Lenses- the two types (convex and concave) and their applications

This describes and explains all about lenses and their applications.

1. Getting To Know Each Getting To Know Each
Other!Other!

2. LensesLenses
(Concave & (Concave &
Convex)Convex)

3. Objectives:Objectives:
1. use ray tracing technique to construct 1. use ray tracing technique to construct
images formed by converging and diverging images formed by converging and diverging
lenses;lenses;
2. describe and locate the image(s) formed
by converging and diverging lenses;
3. cite real life application of converging and
diverging lenses.

4. What are lenses?What are lenses?

5. How do Lenses Work?How do Lenses Work?
Light Rays
Refracted Refracted
RaysRays

6. How do Lenses Work?How do Lenses Work?

7. What are the Two Type of What are the Two Type of
Lenses?Lenses?

8. What are the Two Type of What are the Two Type of
Lenses?Lenses?

9. Two Important points in Locating Two Important points in Locating
Image formed by lenses GraphicallyImage formed by lenses Graphically
VIRTUAL SIDE REAL SIDE

10. Ray Diagramming of lensesRay Diagramming of lenses

11. Three “Most Useful Rays” for Three “Most Useful Rays” for
Ray Diagramming for Ray Diagramming for
LensesLenses

12. Image Construction:Image Construction:
Ray 1:Ray 1: A ray parallel to lens axis passes A ray parallel to lens axis passes
through the far focus through the far focus of a converging lens or of a converging lens or
appears to come from the near focus of a appears to come from the near focus of a
diverging lens.diverging lens.
Converging
Lens
Diverging Lens
FF
Ray 1
FF
Ray 1
2F2F 2F 2F

13. Image Construction:Image Construction:
Ray 2:Ray 2: A ray passing through the A ray passing through the nearnear focal focal
point of a converging lens or proceeding point of a converging lens or proceeding
towardtoward the the farfar focal point of a diverging lens focal point of a diverging lens
is refracted parallel to the lens axis.is refracted parallel to the lens axis.
Converging
Lens
Diverging Lens
FF
Ray 1
FF
Ray 1
Ray 2Ray 2
Ray 2Ray 2

14. Image Construction:Image Construction:
Ray 3:Ray 3: A ray passing through the center of A ray passing through the center of
any lens continues in a straight line. The any lens continues in a straight line. The
refraction at the first surface is balanced by refraction at the first surface is balanced by
the refraction at the second surface.the refraction at the second surface.
Converging
Lens
Diverging Lens
FF
Ray 1
FF
Ray 1
Ray 2
Ray 2
Ray Ray
33
Ray Ray
33

15. Describing the Characteristics of Describing the Characteristics of
the Images formed by the Lensesthe Images formed by the Lenses

16. Describing the Characteristics of Describing the Characteristics of
the Images formed by the Lensesthe Images formed by the Lenses
In Diverging Lenses (Concave)In Diverging Lenses (Concave)
L- BETWEEN 2F AND FL- BETWEEN 2F AND F
O- UPRIGHTO- UPRIGHT
S-REDUCEDS-REDUCED
T- VIRTUALT- VIRTUAL
(REGARDLESS OF THE LOCATION OF THE OBJECT(REGARDLESS OF THE LOCATION OF THE OBJECT

17. Images Tracing PointsImages Tracing Points
Draw an arrow to represent the location of an Draw an arrow to represent the location of an
object, then draw any two of the rays from the object, then draw any two of the rays from the
tip of the arrow. The image is where lines tip of the arrow. The image is where lines
cross.cross.
3. Is it enlarged, diminished, or same
size?
2. Is the image real or
virtual?
1. Is the image erect or
inverted?
•Real images are always on the
opposite side of the lens.
Virtual images are on the
same side.

18. RUBRICSRUBRICS

19. Object Outside 2FObject Outside 2F
1. The image is 1. The image is
invertedinverted, i.e., , i.e.,
opposite to the opposite to the
object orientation.object orientation.
2. The image is 2. The image is realreal, i.e., , i.e.,
formed by actual formed by actual
light on the opposite light on the opposite
side of the lens. side of the lens.
3. The image is 3. The image is
diminished diminished in size, i.e., in size, i.e.,
smaller than the smaller than the
object.object.
Image is located
between F and
2F
FF
FF
2F2F
2F2F
Real;
inverted;
diminishe
d

20. Object at 2FObject at 2F
FF
FF
2F2F
2F2F
Real;
inverted;
same size
1. The image is 1. The image is
invertedinverted, i.e., opposite , i.e., opposite
to the object to the object
orientation.orientation.
2. The image is 2. The image is realreal, i.e., , i.e.,
formed by actual light formed by actual light
on the opposite side of on the opposite side of
lens. lens.
3. The image is 3. The image is the same the same
size size as the object.as the object.
Image is located
at 2F on other
side

21. Object Between 2F and FObject Between 2F and F
FF
FF
2F2F
2F2F
Real;
inverted;
enlarged
1. The image is 1. The image is
invertedinverted, i.e., opposite , i.e., opposite
to the object to the object
orientation.orientation.
2. The image is 2. The image is realreal; ;
formed by actual light formed by actual light
rays on opposite siderays on opposite side
3. The image is 3. The image is enlarged enlarged
in size, i.e., larger than in size, i.e., larger than
the object.the object.
Image is located
beyond 2F

22. Object at Focal Length FObject at Focal Length F
FF
FF
2F2F
2F2F
When the object is located at the focal When the object is located at the focal
length, the rays of light are parallel. The length, the rays of light are parallel. The
lines never cross, and no image is formed.lines never cross, and no image is formed.
Parallel rays;
no image
formed

23. Object Inside FObject Inside F
FF
FF
2F2F
2F2F
Virtual;
erect;
enlarged
1. The image is 1. The image is erecterect, ,
i.e., same orientation as i.e., same orientation as
the object.the object.
2. The image is 2. The image is virtualvirtual, ,
i.e., formed where light i.e., formed where light
does does NOTNOT go. go.
3. The image is 3. The image is enlarged enlarged
in size, i.e., larger than in size, i.e., larger than
the object.the object.
Image is located
on near side of
lens

26. QUESTIONS QUESTIONS
1. How does the image change its size and
location, as the object comes nearer the
convex lens? Concave lens?
Answer: As the object comes nearer the convex
lens, the image appears farther and magnified.
As it comes closer to the convex lens (between
F and V), the image appears upright and
becomes virtual. For all locations of object in
front of a concave lens, the image formed is
always upright, reduced, virtual, and located
between F and V.

27. QUESTIONS QUESTIONS
2. Why is it possible for a concave lens to form
a real image?
Answer: A concave lens cannot form real image
because a real image is formed by intersection
of real refracted rays, and concave lens
spreads out the real rays.

28. ABSTRACTION:ABSTRACTION:
Images formed by a concave lens are virtual,
upright and smaller than the object. The type
of image formed by a convex lens depends on
the distance of the object from the lens.
In tracing the image formed by a lens, any two of
the principal rays may be drawn. Their
intersection locates the position of the image. (a)
Ray passing through the center of the lens is not
deviated. (b) Ray passing through the focus is
refracted parallel to the principal axis. (c) Ray
parallel to the principal axis passes through the
focus after refraction.

29. APPLICATION. Read each situation given, identify the appropriate optical device to be
used. Refer to the size of object and the size of image in the drawn ray diagrams for
convex lens. Identify the location of object for which of the following optical instruments
are used to.
 
SITUATION OPTICAL
INSTRUMENT
SIZE OF THE OBJECT/IMAGE LOCATION OF THE
OBJECT
1. A soldier is on the field doing his daily routine. He
spotted a man walking at a distance. He wanted to
know what the man is doing without going near him.
  Enlarged, Virtual and
Upright
 
2. The teacher is presenting her lesson in front of her
class.
She prepared a Power Point
presentation to be used during class discussion.
  Inverted, Reduce and
Real
 
3. You visit a beach resort near you to enjoy your
summer vacation. You wanted to take the memories
with you back home.
  Inverted, enlarge and
Real
 
4. A group of scientists have
discovered a new nebula lightyear away from earth.
They wanted to observe the activity of the nebula.
  NO IMAGE FORMED  
5. Scientists are tasked to look for a vaccine for
COVID-19 but they wanted to know the structure of
the virus. They also wanted to observe how
the virus works. (eyepiece)
  Enlarged, Erect and
Virtual
 
BINOCULARS BETWEEN F & V
PROJECTOR
CAMERA BETWEEN 2F & F
TELESCOPE AT INFINITY
MICROSCOP
E
BETWEEN F
AND THE
CENTER OFTHE
LENS
BEYOND 2F

30. VALUING VALUING 
Our eyes is an example of a convex lens. Who among
you have vision problems. Share to the class.
Where is the image formed when suffering from a
myopia, hyperopia?

31. Assignment Assignment
1.How does the image change in its size and location as
the object, comes nearer the convex lens?
2.Refer to the size of object and the size of image in the
drawn ray diagrams for convex lens. Identify the location
of object for which of the following optical instruments
are used to. Match column A from column B.
Column A Column B
1.Photocopy “Xerox” Machine a. At infinity
2.Camera b. beyond 2F
3.Telescope c. At 2F
4.Projector d. between 2F and F
5.Magnifying glass e. between F and V

32. CONCLUSION: LensesCONCLUSION: Lenses