2. Mirror
- any surface that is smooth enough to
produce regular or specular reflection
Types of Mirrors
1. Plane Mirrors – mirrors with flat surfaces
2. Spherical Mirrors – mirrors with curve
surfaces
3. Images Formed With Mirrors
1. Real Image - formed in front of a mirror;
it can be projected on a screen; it is
always inverted
2. Virtual Image - it is always found at the
“back” of the mirror; it can not be
focused or projected on a screen; it is
always upright
4. Characteristics of Images
Formed in Plane Mirrors
•
•
•
•
virtual
upright
same size as the object
same distance from the mirror as the
object in front of the mirror
• laterally reversed
5. Spherical Mirrors
- mirrors with curve surfaces; its surface
is taken from the surface of a sphere,
hence the name
Types of Spherical Mirrors:
1. Concave Spherical Mirrors - the
reflecting surface curves inward in the
direction of the incident ray; also
called converging mirrors
2. Convex Spherical Mirrors - the
reflecting surface curves outward to
the incident ray; also called diverging
mirrors
6. Parts of Spherical Mirrors
1. center of curvature ( C ) – center of the sphere where the
mirror was taken
2. vertex ( V ) – center of the mirror, also called pole of the
mirror
3. principal focus ( F ) – the point where the reflected rays
meet; it is midway between C and V
7. Parts of Spherical Mirrors
4. principal axis – straight line joining C and V, also called
optical axis
5. radius of curvature ( R ) – radius of the sphere; distance
between C and V
6. focal length ( f ) – distance from C to F or from V to F; is
equal to half of the radius (R)
7. aperture – width of the mirror (the blue line)
9. Spherical Mirror Equation
OPERATIONAL DEFINITION:
1/f = 1/p + 1/q
where:
f is the focal length
p is the object distance from the mirror
q is the image distance from the mirror
Sign Convention:
+ for distances measured in front of the mirror
- for distances measured behind (back) of the
mirror
10. Mirror Magnification
• Magnification is the ratio of the height of the
image to the height of the object.
OPERATIONAL DEFINITION:
M = hi / ho
M = q/p
11. Mirror Equation & Magnification
1. An object is located 3cm in front of a concave
mirror whose radius of curvature is 12cm. Find:
a. focal length (f) of the mirror
b. distance of the image from the mirror (q)
c. the magnification of the mirror (M)
d. height (hi)of the image if the object is 2cm tall
2. An object 4.5cm high is placed 50cm in front of a
convex mirror with a radius of curvature of
20cm. What is the height of the image?
