Band : B6D1E1

Topic : Understanding light and sight

Instruction : Make a scrap book which is about

the devices to overcome human limitation of

hearing and sense of sight

Binoculars, field glasses or binocular telescopes are a pair

of identical or mirror-symmetrical telescopes mounted

side-by-side and aligned to point accurately in the same

direction, allowing the viewer to use both eyes (binocular

vision) when viewing distant objects. Most are sized to be

held using both hands, although sizes vary widely

from opera glasses to large pedestal mounted military

models. Many different abbreviations are used for

binoculars,

including glasses, nocs, noculars, binos and bins.

Almost from the invention of the telescope in

the 17th century the advantages of mounting

two of them side by side for binocular vision

seems to have been explored.The first binocular

telescope, consisting of two telescopes placed

side by side, was. constructed in 1608 by

Johann Lipperhey, the inventor of the ordinary

Dutch telescope.

Binoculars are essentially a pair of identical

refracting telescopes,they have a large

objective lens at the front and a number of

smaller lenses to enable an image to be

brought into sharp focus.Prisms are used

Almost from the invention of the telescope in

the 17th century the advantages of mounting

two of them side by side for binocular vision

seems to have been explored.The first binocular

telescope, consisting of two telescopes placed

side by side, was. constructed in 1608 by

Johann Lipperhey, the inventor of the ordinary

Dutch telescope.

otherwise they would be limited by distance

between the eyes.The prisms reflect the

image through two angles in the

binoculars .The prisms also reverse the

inversion that occurs.

A telescope is an instrument that aids in the

observation of remote objects by collecting

electromagnetic radiation such as visible

light.It was invented at Netherlands at the

17th century.

It was invented by Galileo

Galilei. He was an

physicist, mathematician,

astronomer,

and philosopher who played a

major role in the Scientific

Revolution. His achievements

include improvements to the

A telescope is a device used to magnify distant objects.If light enters the new

medium at a right angle to the surface (along the normal), it will change

speed, but not direction. If it enters at an angle, its speed and its direction

will change. The direction the light takes depends on whether it travels faster

or slower in the new medium. Imagine driving a car from smooth pavement

onto a sandy beach. If you approach the beach straight on, the car will slow

down, but not change direction. If the you approach the beach at an angle,

one of the tires will be slowed down by the sand before the other is, and the

car will turn in the direction of the tire that touched the sand first.

Light follows the same same principle and bends towards the normal when

traveling into a medium with a higher index of refraction, and away from the

normal when traveling into a medium where it can go faster. In the diagram

below, light is leaving air and entering glass, so it bends. towards the normal

on the way in, and away on the way out of the glass.

A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy.Microscopic means invisible to the eye unless aided by a microscope.

There are many types of microscopes, the most common and first to be invented is theoptical microscope which uses light to image the sample. Other major types of microscopes are the electron microscope (both the transmission electron microscope and the scanning electron microscope) and the various types of scanning probe microscope.

The first microscope to be developed

was the optical microscope, although

the original inventor is not easy to

identify. An early microscope was

made in 1590

in Middelburg,Netherlands. Two eyegla

ss 

n credit. Hans Lippershey (who

developed an early telescope)

To be useful, a microscope must accomplish three things: it must magnify the object you are trying to view, resolve the details of the object, and make these details visible.

Understanding these ideas is the first step to learning how a microscope works. The optical or light microscope uses visible light transmitted through, refracted around, or reflected from a specimen.

Light waves are chaotic; an incandescent light source emits light waves traveling in different paths and of varying wavelengths. Some of the lenses in a microscope bend these light waves into parallel paths, magnify and focus the light at the ocular.

A magnifying glass (called a hand lens in laboratory contexts) is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle to see image.

A sheet magnifier consists of many very narrow concentric ring-shaped lenses, such that the combination acts as a single lens but is much thinner. This arrangement is known as aFresnel lens.

The bane of ants everywhere is Roger Bacon, who invented the classic magnifying glass in 1250. He is credited with the invention of the magnifying glass, although he was following up on the work of earlier studies, who was in his turn influenced by Ibn Sahl's 10th century

A magnifying glass is simply a convex lens meant to be held up to

an object to see it magnified. It is a very simple form of

microscope, and its invention allowed many later breakthroughs

in optics to occur. The magnifying glass is most notably seen in

mystery fiction, and is iconically associated with the fictional

character Sherlock Holmes, who used one to study the scene of a

crime in order to locate clues.

The magnification of a glass is determined by the optical power of

the lens and the distance it is held from the object being viewed

and from the eye. A typical one would be labeled as a 2X

magnifier, implying that the size of objects viewed is doubled,

although this is likely to be better than most average users would

achieve. On the other hand, someone with relatively poor

eyesight could use such a tool to achieve an even higher relative

magnification.

If you look through the lens at the object, you'll see an image that

is right-side up and larger than the original. This is because the

simple lens of the magnifying glass is using the retina and lens of

your eye to create a virtual image, that appears to be closer to

the convex lens of the magnifying glass.

An X-ray generator is a device used to generate X-rays. These

devices are commonly used by radiographers to acquire an x-

ray image of the inside of an object (as in medicine or non-

destructive testing) but they are also used in sterilization or

fluorescence. X-radiation (composed of X-rays) is a form

of electromagnetic radiation.  The wavelengths are shorter than

those of UV rays and longer than of gamma rays. In many

languages, X-radiation is called Röntgen radiation, after Wilhelm

Röntgen, who is usually credited as its discoverer, and who had

named it X-radiation to signify an unknown type of radiation.

Wilhelm Conrad Roentgen is responsible for

having created the very first X-ray. Wilhelm

Conrad Rontgen discovered the X-ray by accident

in 1895. While experimenting with his cathode ray

generator, Rontgen noticed that beam sent out by

the machine was able to penetrate and reach

deeper layers than he ever thought was possible.

As an experiment, Rontgen X-rayed his wife’s

hand and found that the machine captured a

The main component of an X-ray machine is a vacuum tube with a cathode,

or filament, and an anode, which is typically made of tungsten. Electric

current passes through the filament, bringing it up to an extremely high

temperature. Once it reaches a certain level of energy, the filament begins

emitting negatively charged electrons from its surface. The positively

charged tungsten anode attracts these electrons with great force, drawing

them through the vacuum tube at a high speed. When an electron collides

with a tungsten atom, an electron in one of the atom’s lower orbitals gets

knocked away. An electron from a higher orbital takes the place of the

dislodged electron, releasing energy as an X-ray photon during its descent.

The X-ray machine is encased in thick, protective lead shielding, which

prevents these X-ray photons from escaping. A small window in the shield

allows some X-ray photons to exit as a narrow beam is directed toward the

patient. When X-rays hit the patient’s body, some pass through and some

are blocked. Typically, bone blocks the X-rays, while soft tissue allows them

to proceed. An X-ray camera captures the X-rays that pass through the

patient, forming an image on a piece of film.

A hand phone  is also known as a cellular phone, cell phone and

a hand phone.It is a device that can make and receive telephone

calls over a radio link while moving around a wide geographic

area. It does so by connecting to a cellular network provided by

a mobile phone operator, allowing access to the public telephone

network. In addition to telephony, modern mobile phones also

support a wide variety of other services such as text

messaging, MMS, email, Internet access, short-range wireless

communications (infrared, Bluetooth), business applications,

gaming and photography. 

by JohnF.Mitchell and Dr Martin

Cooper of Motorola in 1973, using a handset

weighing1 kg.[4] In 1983, the old mobile phone  was

the first to be commercially available. From 1990 to

2011, worldwide mobile phone subscriptions grew

from 12.4 million to over 6 billion, penetrating about

87% of the global population and reaching

the bottom of the economic pyramid.

Before cell phones, people who really needed mobile-communications ability installed radio telephones in their cars. In the radio-telephone system, there was one central antenna tower per city, and perhaps 25 channels available on that tower. This central antenna meant that the phone in your car needed a powerful transmitter -- big enough to transmit 40 or 50 miles (about 70 km). It also meant that not many people could use radio telephones -- there just were not enough channels.

The genius of the cellular system is the division of a city into small cells. This allows extensive frequency reuse across a city, so that millions of people can use cell phones simultaneously.

A good way to understand the sophistication of a cell phone is to compare it to a CB radio or a walkie-talkie.

The stethoscope is an acoustic medical device for auscultation, or

listening to the internal sounds of an animal or human body. It is

often used to listen to lung and heart sounds. It is also used to

listen to intestines and blood flow in arteries and veins. In

combination with asphygmomanometer, it is commonly used for

measurements of blood pressure. Less commonly, "mechanic's

stethoscopes" are used to listen to internal sounds made by

machines, such as diagnosing a malfunctioning automobile

engine by listening to the sounds of its internal parts.

Stethoscopes can also be used to check scientific vacuum

chambers for leaks, and for various other small-scale acoustic

monitoring tasks. A stet hoscope that intensifies auscultatory

sounds is called phonendoscope.

The stethoscope was invented in France in

1816 by René Laennec at the Necker-Enfants

Malades Hospital in Paris.[1] It consisted of a

wooden tube and was monaural. His device

was similar to the common ear trumpet, a

historical form of hearing aid; indeed, his

invention was almost indistinguishable in

structure and function from the trumpet, which

was commonly called a "microphone". The first

flexible stethoscope of any sort may have been

The doctor holds the stethoscope against the patient's body,

usually to listen to the breath or heartbeat. When the heart beats

or the lung fills with air, it produces small sound vibrations

through the body. These vibrations are picked up and amplified

by the diaphragm. The sound passes into the tube, which

transfers it into the doctor's earpieces. There are also electrical

stethoscopes, which use a kind of microphone to pick up and

amplify the sound. Because electrical stethoscopes can lose or

distort parts of the sound, however, most doctors use the acoustic

version.

Stethoscopes are often used to listen to the heart. A healthy heart

produces a double beat with little or no other noise. These are the

sounds of the heart valves closing. With a stethoscope, a doctor

can detect a heart murmur--a whooshing sound after the heart

beat that can sometimes indicate serious heart troubles. The

exact sound of the murmur can give the doctor cues as to what is

causing it. A stethoscope is also used to detect problems with the

lungs. The doctor has the patient breathe deep and listens for

wheezing or crackling sounds. He will also tap the patient's chest

near the stethoscope and listen to the sound. A healthy lung will

sound hollow, whereas one filled with fluid will not. The

stethoscope can help the doctor detect lung problems such as

asthma, pneumonia and bronchitis.

A loudspeaker (or "speaker") is an electroacoustic transducer that

produces sound in response to an electrical audio signal input. Non-electrical

loudspeakers were developed as accessories to telephone systems, but

electronic amplification by vacuum tube made loudspeakers more generally

useful. The most common form of loudspeaker uses a paper cone supporting

a voice coil electromagnet acting on a permanent magnet, but many other

types exist. Where high fidelity reproduction of sound is required, multiple

loudspeakers may be used, each reproducing a part of the audible frequency

range. Miniature loudspeakers are found in devices such as radio and TV

receivers, and many forms of music players. Larger loudspeaker systems are

used for music, sound reinforcement in theatres and concerts, and in public

address systems.

Johann Philipp Reis installed an electric loudspeaker in

his telephone in 1861.It was capable of reproducing clear

tones, but also could reproduce muffled speech after a few

revisions. Alexander Graham Bell patented his first electric

loudspeaker (capable of reproducing intelligible speech) as part

of his telephone in 1876, which was followed in 1877 by an

improved version from Ernst Siemens. Nikola Tesla reportedly

made a similar device in 1881, but he was not issued a

patent. During this time, Thomas Edison was issued a British

patent for a system using compressed air as an amplifying

mechanism for his early cylinder phonographs, but he

ultimately settled for the familiar metal horn driven by a

When the electrical current flowing through the voice coil changes direction, the coil's polar orientation reverses. This changes the magnetic forces between the voice coil and the permanent magnet, moving the coil and attached diaphragm back and forth.

So how does the fluctuation make the speaker coil move back and forth? The electromagnet is positioned in a constant magnetic field created by a permanent magnet. These two magnets -- the electromagnet and the permanent magnet -- interact with each other as any two magnets do. The positive end of the electromagnet is attracted to the negative pole of the permanent magnetic field, and the negative pole of the electromagnet is repelled by the permanent magnet's negative pole. When the electromagnet's polar orientation switches, so does the direction of repulsion and attraction. In this way, the alternating current constantly reverses the magnetic forces between the voice coil and the permanent magnet. This pushes the coil back and forth rapidly, like a piston.

When the coil moves, it pushes and pulls on the speaker cone. This vibrates the air in front of the speaker, creating sound waves. The electrical audio signal can also be interpreted as a wave. The frequency and amplitude of this wave, which represents the original sound wave, dictates the rate and distance that the voice

coil moves. This, in turn, determines the frequency and amplitude of the sound waves produced by the diaphragm.

A microphone colloquially called a mic or mike. It is an acoustic-to- electric transducer or sensor  that converts sound into an electrical signal. Microphones are used in many applications such as telephones, tape recorders, karaoke systems, hearing aids, motion picture production, live and recorded audio engineering, FRS radios, megaphones, in radio and television broadcasting and in computers for recording voice, speech recognition, VoIP, and for non-acoustic purposes such as ultrasonic checking or knock sensors.

Most microphones today use electromagnetic induction (dynamic microphone), capacitance change (condenser microphone), piezoelectric generation, or light modulation to produce an electrical voltage signal from mechanical vibration.

Both Thomas Alva Edison and Emile

Berliner filed patent applications for

the carbon microphone, in March and June

1877 respectively. After a long legal battle,

Edison emerged the victor, and the Berliner

patent was ruled invalid by both American

Microphones are a type of transducer - a device which converts energy from one form to another. Microphones convert acoustical energy (sound waves) into electrical energy (the audio signal).

Different types of microphone have different ways of converting energy but they all share one thing in common: The diaphragm. This is a thin piece of material (such as paper, plastic or aluminium) which vibrates when it is struck by sound waves. In a typical hand-held mic like the one below, the diaphragm is located in the head of the microphone.When the diaphragm vibrates, it causes other components in the microphone to vibrate. These vibrations are converted into an electrical current which becomes the audio signal. At the other end of the audio chain, the loudspeaker is also a transducer - it converts the electrical energy back into acoustical energy.

Headphones are a pair of small loudspeakers that are

designed to be held in place close to a user's ears.

Headphones either have wires for connection to a signal

source such as an audio amplifier, radio, CD

player, portable media player or mobile phone, or have

a wireless receiver, which is used to pick up signal

without using a cable. earpiece, and were the only way

to listen to electrical audio

signals before amplifiers were

developed. The first truly

successful set was developed by

Nathaniel Baldwin, who made

them by hand in his kitchen.

The human ear depends on a thin membrane, the eardrum, which

vibrates in response to sound waves. The brain translates the

vibrations into what we experience as sound. Speakers create

waves of sound very much like a drum makes noise. When you

strike a drum, the skin of the drum vibrates, creating sound

waves. Speakers start with a cone, and, like a drum, a diaphragm

of paper, fabric or plastic is stretched across the wide part of the

cone, where it is fastened to a metal ring. The smaller end of the

cone contains an iron coil sitting in front of a magnet. The coil is

connected to the wires that connect the speaker to the stereo or

music player. Sound from the source is translated into electrical

signals that turn the coil into an electromagnet. The magnetized

coil either attracts or repels the magnet behind it, which moves

the coil back and forth. The motion of the coil pushes and pulls

the diaphragm, creating waves just like a drum, and pumping

sound waves out from the speaker into the room or straight into

your ear.