The Nature of Sound

This week we studied about sound.A vibration  is the complete back-and-forth motion of an object.
A sound wave is a longitudinal wave that is caused by vibrations and that travels through a material medium.
Sound waves travel in all directions away from their source.
However,air or the other matter does not travel in sound waves.The particles of air only vibrate back and forth.

If air did travel with sound,wind gusts from music speakers would blow you over at a school dance!
But in a vacuum there are no particles to vibrate.
So no sound can be made  in a vacuum.

The many parts of the ear must work together for you  to hear sounds.If any part of the ear is damaged
or does not work properly,hearing loss or deafness may result.
One of the most common types of hearing loss  is called tinnitus.

Conductive Hearing Loss

Conductive hearing loss is the result of disorders in either the outer or middle ear, which prevent sound from getting to the inner ear. Voices and sounds may sound faint, distorted or both.
Some common causes of conductive hearing loss:

• Infection of the ear canal or middle ear
• Fluid in the middle ear
• Perforation or scarring of the eardrum
• Wax build-up
• Dislocation of the ossicles (three middle-ear bones)
• Foreign objects in the ear canal
• Otosclerosis
• Unusual growths, tumors

• Sensorineural

  Hearing Loss

  Sensorineural hearing loss occurs when inner ear nerves become damaged and do not properly transmit their signals to the brain. Patients may complain that people seem to mumble or that they hear, but do not understand, what is being said. The aging process is the most common cause of sensorineural hearing loss. As we get older, the inner ear nerves and sensory cells gradually die.
• If a hearing loss is the result of both conductive and sensorineural components, it is known as a mixed hearing loss.

Ways to prevent hearing loss
Pick the Right Earphones
In a noisy setting, the sound-isolating kind are best, says Brian Fligor, director of diagnostic audiology at Children's Hospital Boston: "They block the right proportion of high and low frequencies so you can hear your music at a lower volume." Noise-canceling headphones are less effective; they block mostly low frequencies.

Swallow Some Protection
Inside our ears lie thousands of hairlike cells that turn sound waves into electrical signals so the brain can interpret what we hear. But very loud noise generates free radicals that damage those cells—sometimes permanently. The U.S. military has been pouring money into research on prevention, and it's paying off. A clinical trial revealed that an over-the-counter supplement called N-acetylcysteine worked much better than earplugs alone at minimizing damage in Marines exposed to gunfire. Researcher Richard D. Kopke, MD, recommends taking 1,200 milligrams 12 hours before you're bombarded by loud noise (say, at a sporting event). If the noise is unexpected, pop 1,200 milligrams as soon as possible and take 900 to 1,200 milligrams three times a day, with meals, for the next 14 days.

PROPERTIES OF SOUND

Pitch a measure of how high or low a sound is perceived to be,depending on the frequency of the sound wave.

 

 

 

 

The doppler effect is the apparent change in the frequency of a sound caused by the motion of either the listener or the source of the sound.The same sound source is radiating sound waves at a constant frequency in the same medium. However, now the sound source is moving to the right with a speed υ_s = 0.7 c (Mach 0.7). The wave-fronts are produced with the same frequency as before. However, since the source is moving, the centre of each new wavefront is now slightly displaced to the right. As a result, the wave-fronts begin to bunch up on the right side (in front of) and spread further apart on the left side (behind) of the source. An observer in front of the source will hear a higher frequency , and an observer behind the source will hear a lower frequency

Species	Approximate Range (Hz)
human	64-23,000
dog	67-45,000
cat	45-64,000
cow	23-35,000
horse	55-33,500
sheep	100-30,000
rabbit	360-42,000
rat	200-76,000
mouse	1,000-91,000
gerbil	100-60,000
guinea pig	54-50,000
hedgehog	250-45,000
raccoon	100-40,000
ferret	16-44,000
opossum	500-64,000
chinchilla	90-22,800
bat	2,000-110,000
beluga whale	1,000-123,000
elephant	16-12,000
porpoise	75-150,000
goldfish	20-3,000
catfish	50-4,000
tuna	50-1,100
bullfrog	100-3,000
tree frog	50-4,000
canary	250-8,000
parakeet	200-8,500
cockatiel	250-8,000
owl	200-12,000
chicken	125-2,000

The nature of waves

This week we talked about the nature of waves.
A wave is a disturbance  that transmits energy through matter or empty space.
Energy can be carried away from its source by a wave.
A medium is a physical environment in which phenomena occur.
Sound waves need a medium.Sound energy travels by the vibration of particles in liquids,solids,and gases.
If there are no particle to vibrate,no sound is possible.
Light waves are electromagnetic waves.And they do not need a medium .
Transverse waves are waves that the particles of the medium move perpendicularly to the direction of the wave is travelling.
A wave on a rope is a transverse waves because the particles of the medium vibrate perpendicularly to the direction the waves moves.
A longitudinal wave is a wave in which  the particles of the medium vibrate  parallel to the direction of wave motion.A part of  a longitudinal wave where the particles are crowded together are called compression.
A part where the particles are spread apart  is a rarefaction.
Sound wave example of a longitudinal wave.
The amplitude is the maximum distance that the particles of a wave's medium vibrate from their rest position.
And the wavelength the distance from any point on a wave to an identical point on the next wave.
Frequency is the number of waves produced in a given amount of time.
And to make high frequency waves in a rope you must shake the rope quickly back and forth.
And wave speed the speed at which waves travels through a medium.

Electronic Technology

Machines can change electrical energy into  other forms  of  energy  to do work.
And  it is used to handle information.A circuit board is a collection of many circuit parts on a sheet of insulating
material.
The way that the television works is that.When you change the channel  or volume  on the television.You push the buttons on the remote control. To send a signal with the correct information to the  television.And the information is sent to the televison in the form of infrared light by tiny bulb called LED.
While the semiconductor is an element  or compound that conducts electric current better than an insulator does but not as well as conductor does.
A diode electronic device  that allows electric charge to move more easily in one direction than in the  other.
Diodes are used in power plants  to send electrical energy to homes by alternating current(AC).But other things  like  radios use direct current.(DC). The diodes are used to help change between AC to DC.
The change between AC to DC occurs  when the diodes in AC adapter block the current in one direction.But then the direction remains.
Transistor is a semiconductor device  that can amplify current and that is used in amplifiers,oscillators and switches.
Oscillator is an electronic circuit that produces a repetitive electronic signal often a sine wave or a   square wave.
Amplifiers is a device for increasing the power of a
signal  by use of an external energy source.
An integrated circuit is an entire circuit that has many components on a single semiconductor.

Communication Technology

The telegraph was one of the first electronic communication devices to send information by using signals.
It was invented in the 1830's.It used  an electric  current to send messages between places joined by wires.
Shows patterns of dots and dashes each standing for a letter and number in the morse code.
Analog signal a signal whose properties can change continuously in a given range.

A digital signal  a signal that can be represented as a sequence of discrete values.
Electromagnetic(EM) is a wave that consists of changing electric and magnetic fields.

COMPUTERS

A computer is an electronic device that performs tasks by following instructions given to it.

The information you give to a computer is called input.The computer processes the input.

Microprocessor a single semi-conductor chip that controls and executes a microcomputer's

instructions.

Hardware is  the parts or pieces of equipment that make up a computer.

COMPUTER HARDWARE

.MICROPHONE

.SPEAKER

.MONITOR

.KEYBOARD

.MOUSE

.CPU

.RAM

.ROM

.CD-ROM DRIVE

.FLOPPY DRIVE

.HARD DISK

.PRINTER

.SCANNER

DIGITIZING PAD AND PEN

CD-ROM

FLOPPY DISK

Software is a set of instructions or commands that tells a computer what to do.

The internet is a large computer network that connects many local and smaller networks all over world.

ElectroMagnetism

Our lesson for this week is electromagnetism.At first more than 2000 years ago the
greeks discovered a mineral that attracts things made of iron.This mineral was found in a place in Turkey.
Thus it was called Magnesia,but the greeks called it magnetite.But today we call it the magnet.
Magnets have two poles.The magnet exerts forces on each other and its surrounded by a magnetic field.
And if you bring two magnets close together it will exert magnetic force.The magnet has the north and south
pole.And the groups of atoms are in tiny areas are called Domains.The north and south pole line up together
to make up a strong magnetic field.Domains are like tiny magnets of different sizes within an object.The magnetic field is the region in which the magnetic forces act.
Also when you cut a magnet in half.You end up having two magnets not one.
FerroMagnets -metals made with these metals have strong magnetic properties.

ElectroMagnet-a magnet  made by electric current and it usually has an iron core.

Electromagnetism is the interaction between electricity and magnetism.Using electromagnetism the
magnetic field is generated by  an electric current in a wire  that can move a compass needle.
The discovery  of  electromagnetism was discovered by the danish scientist by Hans Christian Oersted.
He was the one who discovered the relationship between electricity and magnetism in 1820.
He noticed that when the compass was close to the wire.The compass needle no longer pointed north
.And then he discovered that a compass needle was a  magnet.It moves from its north south orientation
only when it is in a magnetic field different from  Earth's.
Solenoid is a coil of wire that produces  a magnetic field when carrying a electric current.The magnetic
field of a solenoid is very similar to the field of a bar magnet.

Electricity

Our lesson this week is about electricity and  that electricity is helpful in our lives.
Conduction is a flow of electric charge through the use of a medium.Such as a wire or ions
or electrolyte.Induction is the  process of heating an electrically conducting object. Induction
allows the the targeted heating.And also surface hardening.Friction is the friction between two solid

objects that are not moving  relative to each other.

Radioactivity

Hi......Radioactivity ........  is the process of  emitting energy in the form of the waves or particles.
And radiation is generally produced when particles interact or decay.
A  large contribution of the radiation on earth is from the sun (solar)or from radioactive isotopes of the elements(terrestial).Isotope=unstable.......isotopes two or more of an element having  the same number of protons but different number of neutrons.Certain isotopes are  "unstable" and decay.
Alpha particles have a positive charge and it is a kind of decay that gives off  2 protons & 2 neutrons and becomes a Helium nucleus.
And beta particle is a kind if decay and it gives of positron and electron...and in turn makes it negatively charged...
Gamma rays do not have a charge and it is a high energy light particle and it is not visible of the EM spectrum.
The alpha particle is a Helium nucleus and it is the same as the element Helium.