Waves

what are waves

Waves transfer energy from one point to another through vibrations

what are transverse waves

in these waves the particles vibrate perpendicular to the direction of energy transfer .

what are longitudinal waves

these are waves which the particles vibrate parallel to the direction of energy transfer

examples of transverse waves

• Radio waves

• Light rays

• X rays

• Water waves

Example of longitudinal

• sound waves

• Ultrasound waves (sound waves with a frequency greater than 20,000 hz)

wave mechanics

What is amplitude (m)

the maximum displacement of the particles from rest position

What is wavelength λ (m)

The distance between two identical points on the wave

T = time period

The time taken for one complete wave and can only be found if time is on x axis

what is frequency -

Hz - the number of complete waves in one second

Wave equation

V = fλ

• Velocity of wave (m-s)

• Frequency (Hz)

• wavelength (m)

Time period equation

f = 1 ➗T

• Frequency’s

• Time period

what is the human hearing range

20hz to 20,000hz

What is the an ultrasound

a frequency greater than 20,000hz

what is an ultrasound used for in medical uses

pre -natal scans

disintegrating kidney stones

process of prenatal scan

a pulse of ultrasound is directed toward the brain, this is absorbed and passes through the brain, it is then reflected at the far side of the brain and detected back from the sonographer, the equation distance = speed x time shows diameter of the brain

what are the industrial uses for ultrasound

determining the depth of an ocean

cleaning expensive jewellery

detect defects in metals

identify location of fish under boat, - ultrasound returns more quicker than expected

Echo

sonar use reflective soundwaves also known as echo

what is radar

a reflective radio wave . These are used to sims the location of planes approaching airports

properties of radar

• travels very fast (3 × 10⁸)

• can travel through a vacum

• Is transverse

what can sonar be used for

locating slow moving object e.g boats and submarines

fast moving objects e.g planes often travel faster than sound (super sonic) therefore sound waves travel too slow

what are the regions of the EM spectrum

1. Radio waves

2. Microwaves

3. Infrared

4. Visible light

5. Ultraviolet

6. X rags

7. Gamma rays

Longest wave length =

Smallest frequency , least dangerous : radio waves

smallest wavelength =

biggest frequency , most dangerous - gamma rays

Uses and Dangers of Radiowaves

Tv and Radio communication

No known risks

Uses and Dangers of Microwaves

phone calls, parking sensors, rapid heating of food.

Can cause tissue and cells to absrob microwaves and increase temperature

Uses and Dangers of Infrared

Remote control, night vision goggles, toasters and grills

Absorbed as heat energy by tissue/cells results in sun burn

Uses and Dangers of Visible Light

Photosynthesis, photography

Snow blindess, difficulty driving

Uses and Dangers of UV

Used to detect fake bank notes, kills bacteria in water

Absorbed by skin cells, dirsupts DNA causing cancer

Uses and Dangers of X rays

Detects fractures in broken bones, used in security scans at airports

Ionising radiation which dirsupts DNA - cancer

Uses and Dangers of Gamma Rays

based in chemotherapy and radiotherapy to kill cancerous cells

sterilise surgical equipment

highly ionising radiation which disrupt DNA