Optics and Sound: Models, Lenses, and Frequency Analysis Essay

This essay provides a comprehensive overview of key concepts in physics, focusing on optics and sound. It begins by defining light and sound waves, explaining their characteristics and models of movement. The essay then delves into corrective lenses, differentiating between myopia and hyperopia and explaining how concave and convex lenses address these vision impairments. Furthermore, the concept of frequency is explored in relation to sound waves and the human auditory system, detailing the roles of the outer, middle, and inner ear in processing sound. The essay concludes by summarizing the main points, emphasizing the interconnectedness of these physical phenomena and their practical applications. The essay is supported by references to various books, journals, and online resources, including diagrams illustrating the ray model of light, sound wave creation, and vision defects.

Optics & Sound

Table of Contents
INTRODUCTION...........................................................................................................................1
Main Body.......................................................................................................................................1
Models of movement of light and sound waves..........................................................................1
Corrective lenses for short and long sight...................................................................................2
Concept of frequency for detection of sound waves within inner ear.........................................4
Conclusion.......................................................................................................................................4
References........................................................................................................................................4

INTRODUCTION
Physics refers to scientific study of forces like electricity, gravity, pressure, light, sound
and heat, along with ways in which they affects object. It deals with scrutiny of forces, matter
and their effects. Light is defined as disturbance of magnetic and electric fields which travel in
form of waves, known as light waves (Stamnes, 2017). They comprises of high points referred to
crest and low points are troughs. Sound waves refer to longitudinal wave within elastic medium
that is responsible for producing audible sensation. This essay is based on ability to distinguish
among frequencies of light as well as sound waves. Models associated with them, corrective
lenses for both long and short sight. Along with this concept of frequency is illustrated with
respect to sound waves.
Main Body
Light is a electromagnetic and transverse wave is seen by human beings. It is an
electromagnetic wave in which electric field alternates. There exists different ways to describe
light like within quantum mechanics as well as spectroscopy light is not defined as wave but in
the form of waves (Born and Wolf, 2013). It can be defined by usage of ray model of light. In
this, light is described by making use of directions illustrated by arrows which indicates path of
light (An introduction to the models of Light, 2019). A ray denotes a narrow beam of light which
travels within a straight.
(Source: An introduction to the models of Light, 2019)
An example with respect to this is light from laser pointer. It travels in a straight line until
some interface hits it. When mirror or any other interface hits light then direction is changed. The
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Illustration 1: Ray Model of Light

above figure, shows that light is travelling within straight line until it was hit by a prism
(Silverman, 2018).
Sound waves refers to oscillation in velocity, displacement, stress, pressure, etc. which is
which is experienced by a particle while propagating in a medium with internal forces. It is a
form of energy which makes individual to hear. Basically, it is a variation in pressure, a region in
which there exists high pressure denotes compression and alternative is known as rarefaction.
The concept of movement of sound waves can be illustrated by taking an example like sound
waves are produced by vibrating objects (Brekhovskikh, 2012). Tuning fork creates longitudinal
waves. The tines of fork vibrates within back as well as forth direction which pushes
neighbouring air particles. Due to longitudinal motion of air particles, there are regions in which
particles are compressed and some regions are there in which they spread. This is referred to
compression and rarefactions respectively.
(Source: Sound is a Pressure Wave, 2019)
The sound waves are created by tuning fork and propagated through open tube.
Basically, sound waves comprises of repeated pattern of high and low pressure regions which
travels through some medium (Holman, 2012).
Short sightedness is referred to myopia which is a visual impairment. It is when
individual is not able to see objects which are at distance but can see near objects. In this, image
is focussed in front of retina rather than on it as refractive power of eye's lens is too strong. To
correct this problem, lens must be diminished. To weaken the lens, negative or diverging lens
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Illustration 2:
Sound Wave created through Tuning Fork

can be used, they are concave lens. Diverging lens are wider at middle as a result of which light
spreads out even if light is passed through lens before.
(Source: 2.2 Defects of Vision and Their Correction, 2019)
Long sightedness is also known as hyperopia or farsightedness as people with this
(hyperopia) focus on faraway objects as near objects become blur. In this case, eye is short for
the lens, process of accumulation is not enough for focussing on light which is from more closer
objects on retina. As these objects are focused from behind of retina it makes, objects look
blurry. This can be corrected by usage of positive or converging artificial lens, they are convex
lenses. These lenses are wider at middle as compared to edges which adds more power in terms
of focussing in eye.
Frequency is defined as speed of vibration which identify pitch of of sound. Basically, it
denotes pitch which can be high or low and it comprises of entire sound wave cycles each
second. For hearing a sound the auditory system needs to execute three primary tasks. The initial
task is to present acoustic stimulus to receptors (Moore, 2012). Other is to transform stimulus
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Illustration 3: Myopia and Hyperopia

from pressure to electrical signal and the last is to process the signals that are attained. This will
indicate qualities of sound source like pitch (frequency) and volume or loudness (amplitude).
Human ears are divided into three major functional segments, they are illustrated below:
 Outer ear: They gather sound energy from environment and that is sent to eardrum. It
consists of auricle or pinna.
 Middle ear: In this mechanical pressure is transduced from ear drum into electrical
signals.
 Inner ear: It consists of both balance and hearing organs. It takes electrical signal which
is generated by middle ear by making use of hair cells (sensory cells linked with central
hearing system by auditory or hearing nerve).
When sound is heard by an individual then these steps occur:
 Sound waves get into ear canal and it makes eardrum to vibrate. Then vibrations are
passed by 3 connected bones within middle ear (Leighton, 2012).
 By this fluid is set moving within the inner ear and it blends various delicate hair-cells
which will transform vibrations to nerve impulses.
 These impulses will be carried to brain through auditory nerve. Within brain, impulses
are transformed into sound.
Conclusion
From above it can be concluded that, physics refers to branch of science which is
associated with nature as well as properties of energy and matter. Light waves are defined as
electromagnetic waves through which light travels in a vacuum or via some medium. Sound
waves are referred to compression and rarefaction through which sound is propagated within
elastic medium. The three layers within ear enables sound of certain frequency into the ear drum
and electrical signals are generated within inner ear. Impulses are transformed to sounds through
auditory nerve.
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References
Books & Journals
Born, M. and Wolf, E., 2013. Principles of optics: electromagnetic theory of propagation,
interference and diffraction of light. Elsevier.
Brekhovskikh, L., 2012. Waves in layered media (Vol. 16). Elsevier.
Holman, T., 2012. Sound for film and television. Focal press.
Leighton, T., 2012. The acoustic bubble. Academic press.
Moore, B. C., 2012. An introduction to the psychology of hearing. Brill.
Silverman, M. P., 2018. Waves and grains: reflections on light and learning. Princeton
University Press.
Stamnes, J. J., 2017. Waves in focal regions: propagation, diffraction and focusing of light,
sound and water waves. Routledge.
Online
An introduction to the models of Light. 2019. [Online]. Available through:
<https://www.azooptics.com/Article.aspx?ArticleID=8>.
Sound is a Pressure Wave. 2019. [Online].
<https://www.physicsclassroom.com/class/sound/Lesson-1/Sound-is-a-Pressure-Wave>.
2.2 Defects of Vision and Their Correction. 2019. [Online]. Available through:
<https://www.ck12.org/book/CBSE-Physics-Book-Class-X/section/2.2/>.
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