Waves (paper 2) Flashcards
What is a wave?
a transfer of energy from one point to another
name the two types of waves and there definitions
- Mechanical waves ~ waves that vibrate through a medium (a substance)
- Electromagnetic waves ~ waves which can travel through a vacuum (no medium is needed)
transverse wave
The oscillations of a transverse wave are perpendicular to the direction in which the waves transfer energy
longitudinal wave
The oscillations of a longitudinal wave are parallel to the distance in which the waves transfer energy
what type of waves are electromagnetic waves
- transverse
what type of waves are mechanical waves
- transverse
- longitudinal
What is amplitude?
maximum displacement of a point on the wave from its undisturbed position.
what is the wavelength of a wave?
the distance from a point on the wave to the equivalent point on the adjacent wave
what is frequency?
number of waves passing a fixed point per second
What is the frequency equation?
Period (seconds) = 1/frequency
T (s) = 1/F (Hz)
What is wave speed?
distance travelled by each wave per second
What is the wave speed equation?
Wave speed = frequency x wavelength
V (m/s) = f (Hz) x λ (m)
What are sound waves?
Vibrations that travel through a medium
What are ultrasound waves?
waves above the frequency of 20kH^2 (20000H^2)
What is the equation for distance?
Distance = speed x time
How are seismic waves produced?
They are produced in an earthquake. They spread out from the epicentre
What is the epicenter?
The nearest point on the surface to where the earthquake originates.
What types of waves do earthquakes create?
- primary seismic waves (P-waves) that are longitudinal
- secondary seismic waves (S-waves) that are transverse
How fast do electromagnetic waves travel in a vacuum?
3x10^8m/s
List the electromagnetic spectrum in stating the order of increasing frequency and increasing wavelength
increasing frequency —->
Radio ~ Microwave ~ Infrared ~ visible ~ ultraviolet ~ x-ray ~ gamma
<—-increasing wavelength
uses of infrared
- optical fibers
- remote controls
- ovens
- thermal imaging
Uses of microwaves
- Navigation
- cooking
- drying
- mobile phones
uses of visible light
- photosynthesis
- optical fibers
- torches
- cameras
What are gamma rays 2 main uses
- killing harmful bacteria in food or on surgical equipment
- cancer treatment
What is the main use of x-rays
medical imaging
What is ionisation?
When an atom loses an electron. One cause of this is x-rays or gamma rays passing through a substance. If ionisation happens to living cells it can damage cells and potentially cause cancer
How can x-rays be blocked?
- bones
- teeth
-metal inside body
How can you x-ray soft tissue organs?
By filling them with a contrast medium that absorbs x-rays
define peak
highest point above the rest position
define trough
lowest point
Explain the changes in air pressure caused by longitudinal waves in regions of compression and rarefaction.
- compression ~ the air particles are close together resulting in high pressure
- rarefaction ~ air particles are spread further apart leading to low pressure
approximate range of wavelengths
10^-15 m – 10^4 m
what is the only part of the electromagnetic spectrum that our eyes can detect?
visible light
from the electromagnetic spectrum, give the name and use of a radiation of lower frequency than light
- microwave
- cooking
name 3 types of electromagnetic spectrum radiation which has more energy than infrared
- visible light
- x-ray
- gamma ray
- the wavelength of infrared is… the wavelength of microwaves
- the frequency of microwaves is… the frequency of infrared
- the speed of microwave in a vacuum is… the speed of infrared in a vacuum
- less than
- less than
- the same as
X-rays can be dangerous to people because X-rays are… radiation
ionising
a student finds it difficult to measure ripples on the surface of some water in a ripple tank because the ripples are moving. Suggest and explain what the student could do to make the measurement easier.
- student can use strobe light
- when the strobe light matches the length of the waves the waves fronts will appear stationary
uses of ultrasound
- breaking kidney stones
- cleaning jewellery
describe how the wavelength of the water waves in a ripple tank can be measured accurately
measure length of the number of waves then divide by the number of the waves
state the name given to reflected sound waves
echo
state one industrial use for ultrasound
cleaning
state one medical use for ultrasound
pre-natal scanning
