Waves - Science Topic 4

Might be in science Term 4 test who knows??

What is vibration?

Vibration is movement back and forth or up and down a point of equillbrium

What are waves?

Waves are the transfer of energy without the transfer of matter

What are the two basic subtypes of waves?

Transverse waves and longitudinal waves

Describe the movement in a transverse wave

The particles move up and down, at right angles to the direction of the wave

Give three examples of transverse waves

• Water waves

• Electromagnetic waves

• S-waves

What are the two parts of a transverse wave?

Crests and troughs

Describe the movement in a longitudinal wave

The particles vibrate back and forth, so the direction of their movement is parallel to the direction of the wave

Give two examples of longitudinal waves

• Sound waves

• P-waves of earthquakes

What are the two parts of longitudinal waves?

Compressions and rarefactions

What is the wavelength?

The wavelength is the distance between two matchin points on neighbouring waves

What is the amplitude?

The amplitude of any wave is the maximum a point moves from its rest position

What does an oscilloscope display?

An oscilloscope displays wave forms that would otherwise be invisible to the human eye

(SOUND) If there is greater amplitude there is…

Louder sound (greater volume)

(SOUND) If there is greater frequency there is…

Higher pitch

(SOUND) If there is shorter wavelength there is…

Higher pitch

What is the frequency?

The frequency is the number of waves passing a point each second

1 wave per second =

1 Hz

What is the formula for velocity

Frequency x wavelength

What is the period?

The time for one wavelength to pass a point

What is the formula for period?

1 divided by frequency

What is the formula for frequency?

1 divided by period

In a vacuum (space) at what speed do waves travel?

300 000 km/s

List the electromagnetic spectrum

Radio waves

Microwaves

Infrared

Visible

Ultraviolet

X-ray

Gamma rays

Which wave has the longest Wavelength, lowest Frequency, and lowest energy

Radiowaves

Which wave has the shortest Wavelength, highest Frequency and highest energy

Gamma rays

What are the two uses of Radio waves?

• Broadcasting communications

• Bluetooth

How dangerous are Radio waves?

They are harmless, only very high levels can heat and burn tissue

What are the three uses of microwaves?

• Cooking

• Satellite transmissions

• Mobile phones

How dangerous are microwaves?

They have potential danger, microwaves can heat and burn tissue

What are the five uses of infrared radiation

• Cooking

• Thermal imaging

• Optical fibres

• Television remote controls

• Security systems

How dangerous is infrared radiation?

They have potential danger, infrared radiation is felt as heat and causes skin burns

What are the two uses of visible light?

• Photography

• Illumination

How dangerous is visible light?

It has potential danger, staring directly at bright light can cause damage to the retina

Which waves are forms of ionising radiation?

• Ultraviolet

• X-rays

• Gamma rays

What are four uses of ultraviolet radiation?

• Security marking

• Fluorescent lamps

• Disinfecting

• Sun beds

How dangerous is Ultraviolet?

Potential danger, skin damage and skin cancer

What are the three uses of X-rays?

• Observing the internal structure of objects

• Airport security scanners

• Medical scanners

How dangerous are X-rays?

They have potential danger, X-rays can damage cells, destroy cells, and cause mutations that lead to skin cancer

What are the two uses of Gamma rays?

• Sterilising food and medical equipment

• Cancer treatment

How dangerous are Gamma rays?

They have potential danger since they can damage cells, destroy cells, and cause mutations that lead to cancer

What is heat energy

Heat energy is the flow or transfer of energy from a warmer object to a cooler object due to difference in temperature

What is heat?

Heat is the energy transfer that takes place between objects of different temperatures

What is Heat measured in?

Joules

When does heat transfer occur?

Heat transfer only occurs when there is a temperature difference between substances

What is the way heat always moves?

Heat always moves from an area of higher temperature to an area of lower temperature

What is the difference between heat and thermal energy

The difference is that thermal energy is not in the process of being transferred

What is the thermal energy of an object?

The thermal energy of an object is the energy contained in the vibration of its atoms and molecules

What does thermal energy refer to?

Thermal energy refers to the energy contained within a system that is responsible for its temperature

What is temperature?

Temperature is a measure of how hot or cold an object is

What is temperature determined by?

Temperature is determined by the average kinetic energy of the particles in an object

What is temperature measured in?

Degrees celsius

What is thermal radiation emitted by?

All objects with a temperature greater than absolute zero

Can thermal radiation travel through a vacuum?

Yes

Why does sound travel?

Sound travels because a vibrating object makes nearby particles vibrate

What does sound need to travel through?

Sound needs a medium to travel through

Can sound travel through a vacuum (ie space) ?

No

Why does sound travel faster through liquids and solids than it does through air and other gases?

Because particles of gases are further apart than liquids and finally solids

What do we use to measure loudness?

The decibel scale

Why does sound travel faster in solids?

Sound travels faster in solids because the tightly packed atoms/molecules in a solid transfer vibrational energy more efficiently than in liquids and gases

Describe how the sound is affected by the length of a vibrating string

Lower frequency, lower pitch

Describe how the sound produced is affected by the tension of the string

Higher tension, higher pitch

Describe how the sound produced is affected by the thickness of string

Greater thickness, lower pitch

What is the range of frequencies a person can hear called?

Their hearing range

What is the hearing range of a healthy young person?

20Hz ot 20 000 Hz

How many people suffer from some sort of hearing loss?

1 in 5 people

What can temporary hearing loss be caused by?

Temporary hearing loss can be cause by ear infections and colds, after which hearing recovers

What can permanent hearing loss be caused by?

Permanent hearing loss and deafness can be present at birth and occur if the ear is damaged or diseased

What is ultrasound?

Ultrasound is a sound with a frequency of more than 20,000 Hz

What is one way ultrasound is used in medicine?

To check the health of unborn

Why are ultrasounds used instead of x-rays to check the health of an unborn baby?

Ultrasound scans are much safer than X-rays because X-rays can damage cells in the body of the mother and the baby

Why is ultrasound also used in sonar?

Ultrasound is used in sonar to produce images of underwater objects or the ocean floor

What do we call sound we can’t hear?

Ultrasound

Which parts of a baby’s body show up on an ultrasound scan?

Soft tissue and organs

What is ultrasound gel?

Ultrasound gel is a conductive medium that enables a tight bond between the skin and the probe

Why is it useful to have a moving picture in an ultrasound?

They can show the structure and the movement of the body’s internal organs, as well as the blood flowing through the vessels

Label part 1

Ear canal

Label part 2

The pinna

(DN) Label part 3

Small bones

Label part 4

The auditory nerve

Label part 5

Cochlea

Label part 6

Eardrum

Label part 7

Hammer

Label part 8

Anvil

Label part 9

Stirrup

How does the ear hear? (6 steps)

1. Sound waves are collected by the outer ear or pinna

2. The waves travel along the ear canal 

3. The waves make the ear drum vibrate

4. The small bones (ossicles) amplify the vibrations

5. The cochlea turns these into electrical signals

6. The auditory nerve takes the signals to the brain

List 4 - 7 causes of hearing loss

• Prolonged exposure to loud sounds can damage the cochlea

• Loud noises or impacts to the head can burst the ear drum or damage ossicles

• Ear infections can block the ear canal 

• Ear wax buildup can block the ear canal 

Various other causes: tumours, medications, birth defects

In treating hearing loss what does a hearing aid do?

Magnify sound

In treating hearing loss what does a bone conduction implant do?

Sends sound vibrations directly through the skull bone to the inner ear, bypassing the damaged middle ear

In treating hearing loss what does a cochlear implant do?

It detects sound using a microphone and produces an electrical signal that directly stimulates the auditory nerve

List four sources of light energy

• The sun

• Light globes

• Fires

• Some animals

How can we prove that light always travels in straight lines?

Light casts shadows, a shadow is produced in the same shape of that blockage… it doesn’t bend around

What does it mean for an object to be transparent?

Allows light to pass through so that objects behind can be distinctly seen

What does it mean for an object to be transluscent?

Allows light, but not detailed shapes to pass through

What does it mean for an object to be opaque?

Not able to be seen through

What is transmission?

Transmission is when light passes through the material

What is reflection?

Reflection is when light bounces off a shiny surface

What is absorption?

Absorption is when the light energy is absorbed (taken in) by the material

What type of reflection do smooth surfaces give?

A clear reflection

What type of reflection do rough surfaces have?

A diffuse reflection

What is a diffuse reflection?

A diffuse reflection is when light is scattered in different directions