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PBS Ting 2 Science (B6D1E1)

R.Sri Haaran M.Ramesh

on 28 April 2013

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2A1 TECHNOLOGICAL DEVICES TO OVERCOME LIMITATION OF SIGHT AND HEARING Introduction OBJECTIVE The limitation of sight and hearing The Limitation of Sight:- The Limitations of Hearing: •Children have eardrums that are more elastic.

•As people age, their hearing deteriorates. Their eardrums become less elastic.

•Person exposed to constant loud noise experiences a loss of hearing-range of hearing is smaller than normal people. TECHNOLOGICAL DEVICES TO OVERCOME LIMITATION OF SIGHT 1. MICROPHONE Microphone 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, and others. Sight Limitations Hearing LimitationsLimitation of sightDevices to overcome Limitations of sight is whereby a person is able to see an object/colour/shape until a certain extend. Limitations of sight can be overcome by using appropriate optical devices such as Microscope , Telescope , Periscope and others. Hearing Limitations The range of frequency of hearing in human is from 20 Hz to 20000Hz. It is different according to the age of a person. Limitation of hearing can be overcome by using appropriate hearing aids such as microphone, stethoscope, amplifier and others. The objectives of learning about the limitation of sight and hearing:-
I have learnt that our hearing and sight has its limitation.
I have learnt that we can overcome the limitation of our sight and hearing by using or wearing technology devices.
The technology devices have made our live easier:-
i) Doctors use stethoscopes to hear our heartbeats.
ii) Teachers use microphone in the assembly.
iii) Scientists use microscope to see the virus. Optical Illusion -
Sometimes what we see may not appear to be the real thing. This is because the brain cannot interpret accurately what is actually seen by the eye. Optical Illusion -
Sometimes what we see may not appear to be the real thing. This is because the brain cannot interpret accurately what is actually seen by the eye. Blind Spot -
The blind spot is a point of the retina of the eye that cannot detect any image. 1. MICROSCOPE Instrument to magnify object such as virus.

Objective lens and eyepiece magnify image.

The first microscope invented by Sacharias Jansen in 1611. 2. TELESCOPE Viewing very far objects - Stars, Planets and Moon.

Consists of two convex lenses - objective and eyepiece lens.

The image produced by the objective lens is magnified by the eyepiece lens.

The first known practical telescopes were invented in Netherlands.

An instrument that aids in the observation of remote objects by collecting electromagnetic radiation. 3. PERISCOPE To see a view beyond and obstructing object.

An instrument for observation from a concealed position.

Consists of an outer case with mirrors at each end set parallel to each other at 45 degree angle. 4. BINOCULAR To see tiny distant objects such as birds in the sky.

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 when viewing distant objects. 5. MAGNIFYING GLASS To make tiny objects appear larger than the original.

Convex lens that is used to produce a magnified image of an object.

Also called a hand lens in laboratory contexts. 6. ULTRASOUND MACHINE
To scan and see the condition of the baby in a pregnant mother.

A cyclic sound pressure wave with frequency greater than the upper limit of the human hearing range.

This is used for obstetrics, for heart and for biopsy Ultrasonic waves - create images -organ, fetus.

Device shaped like microphone is pressed against the area being scanned.

This device sends out very high frequency sound waves into the area being scanned.

The waves bounce back upon hitting an organ and an image of the organ is then obtained on computer screen. 7. X-RAY MACHINE To see the internal organs.

To inspect baggage at the airports.

This is inverted by Wilhelm Conrad Röntgen a German physicist on 8 November 1895.

Types of x-ray machines:-
1. CT Scanner
2. Bone X-Ray Machine
3. Backscatter X-Ray Machine
4. Linear Accelerator
5. X-Ray Fluorescence (XRF) TECHNOLOGICAL DEVICES TO OVERCOME LIMITATION OF HEARING 2. STETHOSCOPE Allows medical professionals to listen to sounds produced by the lungs, heart and intestines. Any abnormal function within these systems in the body can be immediately spotted with proper use of a stethoscope.

Invented in France by Rene Laennec.

A stethoscope that intensifies auscultatory sounds is called phonendoscope. 3. MEGAPHONE Boosts weak sounds ( the function of Megaphone as same as Microphone )

Invented by Samuel Morland and Athanasius Kircher in 1655.

The term ‘megaphone’ was first associated with Thomas Edison’s instrument 200 years later. 4. EARPHONE Collects and amplifies sounds before sending them to the middle ear.

Invented by Nathaniel Baldwin in 1937.

They are sometimes known as ear speakers or, colloquially, cans.

The in-ear versions are also known as earphones or earbuds. 5. PUBLIC ADDRESS SYSTEM (PA SYSTEM) A public address system (PA system) is an electronic sound amplification and distribution system with a microphone, amplifier and loudspeakers, used to allow a person to address a large public.

Amplifies voices so that they can be heard from far away.

Simple PA systems are often used in small venues such as school auditoriums, churches, and small bars.

Invented by Edwin Jensen and Peter Pridham. Thank You
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