This document discusses reflection of light in plane mirrors. It begins by stating the objectives which are to discuss the property of reflection, explain how images are formed in plane mirrors, and predict the characteristics of images. It then defines the law of reflection and explains that images formed by plane mirrors are virtual, upright, the same size as the object, and laterally reversed. An example is given of a girl using a mirror and how her image would appear based on these characteristics.

1. GOOD MORNING!

2. LESSON: REFLECTION OF
LIGHT IN PLANE MIRRORS

3. OBJECTIVES:
a. Discuss the property of reflection
b. Explain how an image is formed in plane
mirror.
c. Predict the qualitative characteristics
(orientation, type, and magnification) of
images formed by plane mirror.

4. LAWOF REFLECTION
The angle of reflection r is equal to the angle of incidence i.
The reflected and incident rays are also in the same plane.

5. SPECULAR & DIFFUSE REFLECTION

6. REFLECTION
Reflection of light is the bouncing of light from a
reflecting surface.
Reflection can be thought of as light “bouncing
off” a surface (although this phenomena is much
more complex).
Regular (specular) reflection – reflection from very
smooth (mirror) surfaces
Irregular (diffuse) reflection – reflection from
relatively rough surfaces

7. REFLECTION OF LIGHT IN
PLANE MIRRORS
Images formed by plane mirrors are always
virtual, upright, the same size as the object,
the same distance behind the mirror as the
object is in front of the mirror, and laterally
reversed. Laterally reversed means that left
of the object becomes the right of the
image, and vice versa.

8. REFLECTION OF LIGHT
Reflection is the bouncing off of light rays when
it hits a surface like a plane mirror.
Real Image – formed in front of the mirror and is
always upside down relative to the object. It can
be projected on a screen placed in front of
mirror.
Virtual Image – formed behind the mirror and is
upright relative to the object and cannot be
projected on a screen.

9. REFLECTION OF LIGHT IN
PLANE MIRRORS
Suppose that a girl, with a sitting height
of 3ft, is facing 2 ft away from a plane
mirror as she puts blush-on on her right
cheek. Describe the image formed by
each mirror.

10. REFLECTION OF LIGHT IN
PLANE MIRRORS
Explanation: We are given that the girl is 2ft
away from the mirror. Recall that images formed
by plane mirrors are always virtual, upright, the
same size as the object, the same distance
behind the mirror as the object is in front of the
mirror, and laterally reversed. So the girl will see
her image in mirror that is 2ft at its back,
meaning it is virtual. It is sitting at the same size
of 3.5ft height and the image will tell us that she
is putting blush-on on her left cheek.

11. LEARN MORE!
To learn more about our lesson, open the
file Reflection of Light and Image
Formation in this link:
http://www.physicsclassroom.com/class/
refln/Lesson-3/Reflection-of-Light-and-
Image-Formation

12. QUIZTIME!
Let’s check your understanding of our
lesson. Answer ASSESSMENT on
page 32-33 0n a ¼ sheet of paper.