Large font 2D
PHYSICS
LESSON 2: a. Law of reflection b. Plane mirror
A- Law of reflection:
a. Incident ray: ray of
light that come into the
mirror
b. Reflected ray: ray of
light that bounces off
the mirror
c. Normal: line
perpendicular to the
mirror
d. Angle of incidence:
angle between incident
ray and the normal
e. Angle of reflection: angle between reflected ray and the
normal
The Law of Reflection states that:
1. The angle of reflection r = the angle of incidence i
2. The reflected ray and the incident ray are on opposite sides
of the normal
3. The reflected ray, the incidence ray and the normal are on
the same plane
BPLANE MIRROR (or flat mirror)
When light hits an object, every part of that object reflects light
in all direction. Some of the reflected light reaches our eyes.
Thus, we can see the object
Ray diagram is a tool used to show how light travel from
objects
Ray diagram for plane mirror:
When drawing the ray diagram for plane mirror:
1. Only need to extend 2 reflected rays behind the mirror to get
the virtual image
2. Any ray that comes in perpendicular to the mirror will get
reflected the same path
Characteristics of images formed by a plane mirrors:
virtual (not real) image
a. Type of
image:
b. Location: the virtual image is behind the mirrors
The virtual image is always oriented in the same
c.
Orientation: direction as the object
d. Size:
The size of the virtual image = the size of the
object. In other word, the object does not get
magnified by a plane mirror
E.g. If a 1.6-meter tall person stands in front of
a mirror, he/she will see an image which is 1.6meters tall
e. Image
distance:
The image distance di (distance from the image
to the mirror) = the object distance do (distance
from the object to the mirror)
Drawing image in a plane mirror:
Practice questions:
A. PLANE MIRROR:
1.
If Suzie stands 3 feet in front of a plane mirror, how far
from where she stands will her image be located?
2.
Practice drawing ray diagram for plane mirror:
a.
b.
c.
d.
e.
3. State all the characteristics of the images formed from
plane mirrors?