78
field is an acoustic field where sound waves reach the receiver from all directions
directly or indirectly by reflection.
In free acoustic field, there are no reflections. Receiver receives sound directly
from the sound source.
2.6.3 Sound Intensity
Sound power per unit area is called sound intensity.
2.6.4 Intensity Level
The intensity level is defined by:
IL
o
=
(
)
10 10
log
/
I I
Where
Table 2.9 Definition of common terms with respect to mirror
Sl.
no.
Term
Description
1.
Plane mirror
Mirror with a flat (planar) reflective surface
2.
Convex mirror
Mirror with reflective surfaces that curve outward; convex mirrors
reflect light outward
3.
Concave mirror
Mirror with reflective surfaces that curve inward; convex mirrors
reflect light inward
4.
Focal point of
mirror
Point in space where parallel light rays meet after reflecting through
the mirror
5.
Focal length
mirror
Distance between the center of a mirror and its focal point
6.
Optical axis of
lens
Straight line that passes through its center of curvature and geometric
center
Incident Ray
Reflected Ray
Normal
Angle of
Incident
Angle of
Reflection
Fig. 2.25 Line diagram of
incident ray and
reflected ray
2 Fundamentals of Physics for Environmental and Medical Professionals