topic 6: waves Flashcards
What are the two types of waves?
transverse
longitudinal
What is a transverse wave?
Away for which the oscillations are perpendicular to the direction of energy transfer
what is a longitudinal wave
Away for which the oscillations are parallel to the direction of the energy transfer
Give two examples of transverse waves
electromagnetic waves
seismic s-waves
Give two examples of longitudinal waves
sound waves
seismic p-waves
What are the two parts of a longitudinal wave called?
compressions and rarefactions
What is a wave amplitude?
The maximum displacement of a pint on a wave from its disturbed position
what is a wavelength?
The distance from a point on a wave to the same position on the adjacent wave
Most commonly peak to peak or trough to trough
What is a frequency of the wave?
The number of waves that passed a given point each second
what unit is used for frequency?
hertz,Hz
What is meant by frequency of 200 HZ?
200 waves past a given point each second
What is a wave speed?
The speed at which the wave moves or at which energy is transferred through a medium 
What does a wave transfer?
Energy
what word is used to describe when a wave bounces of a surface 
Reflection
How do you sound waves travel through a solid?
The particles in a solid vibrate and transferred kinetic energy through the material
What is the frequency range of human hearing?
20HZ-20kHz
what are ultrasound waves?
Waves which have a frequency higher than the upper limit of human hearing
give an example use for ultrasound waves
Medical or industrial imaging
what natural event causes seismic waves to be produced? What types are produced?
Earthquakes
They produce both P waves and S waves
State the difference between the mediums that P waves and S waves can travel through
P. Waves travel through both solids and liquids.
S waves only travel through solids
what technique is used to detect objects in deep water and measure water depth
echo sounding
High frequency sound waves are emitted reflected and detected
Time difference between a mission and detection alongside wave speed are used to calculate distances
what do our bodies emit and absorb?
Infrared radiation
what happens to the quantity of infrared radiation emitted by an object as temperature increases?
The hotter the object the more infrared radiation it will emit
what is the perfect black body?
An object that absorbs all of the radiation that is incident upon it
how much radiation does a perfect black body reflect or transmit?
None
why is a perfect black body the best possible emmiter of radiation?

it is a perfect absorber since it absorbs our radiation incident on it
A perfect absorber is also a perfect emmiter
Other than the intensity of radiation omitted how does increasing the temperature of an object affect its emissions?
The wavelength for distribution of any emission is dependent on the object temperature
what can be said about the rates of emission and absorption for a body at constant temperature?
The body is absorbing and emitting radiation at the same rate
What can be said about the rates of emission and absorbing for a body increasing in temperature?
The body it is absorbing radiation faster than it is admitting it
Give two factors that affect the temperature of the earth
The Earth rate of absorption and emission of radiation
The amount of reflection of radiation into space
what type of spectrum do electromagnet waves form?
A continuous spectrum
Over types of electromagnetic radiation from lowest to highest frequency
Radio waves
Microwave
Infrared
Visible light
Ultraviolet
X-rays
Gamma rays
how do the speeds of EM radiation differ in a vacuum and in air?
Electromagnetic waves or travel at the same speed in a vacuum and in air
What property of waves in different mediums causes refraction?
velocity
Wave speed is slower in dense materials, causing refraction
In which direction do ways refract when entering a dense medium
They bend towards the normal
The angle of refraction is less than the angle of incidence
what type of waves can be produced by oscillations in electrical circuit?
Radio waves
how can radio waves create an alternative current in a circuit?
When radio waves are absorbed, they can induce oscillations in a circuit with the same frequency as the waves themselves
where do gamma rays originate from?
They originate from changes in the nuclei of atoms
what health affects can ultraviolet waves cause?
It can cause a skin to age prematurely
They can increase the risk of developing skin cancer
what effects can x-rays and gamma rays cause
they are ionising radiation so can cause mutation in genes
They can lead to increase risk of developing various cancer
give three practical uses for infrared radiation
electrical heater
Food cooking
Infrared cameras
Give two practical duties for microwave radiation
satellite communications
Cooking food
Two practical uses for radio waves
television transmission
Radio transmission
What wave phenomenon is used by lenses to form an image?
Refraction
How does a convex lens form an image?
Parallel rays of light are refracted and brought together at a point known as the principle focus
what is meant by the focal length of a lens?
The distance from the lens to the principal focus
what is the difference between the image produced by convex and a concave lens?
Convex lenses can produce real or virtual images
Conveyed lenses can only produce virtual images
why does magnification not have a unit?
It is the ratio between image height and object height
Ratios do not require Units
What determines the colour of visible light waves?
The wavelength and frequency of the light waves
what colour are visible light has the highest frequency
Blue
What colour are visible light has the largest wavelength
red
What is meant by the term specular reflection?
Reflection from a smooth surface in a single direction
what is meant by the term diffuse reflection?
Reflection from a rough surface which causes scattering
How does a red colour filter Work?
A red filter absorbs all wavelength of light other than those in the red range of the spectrum
This means only red light passes through the filter
what determines the colour of an opaque object?
Different objects reflect different wavelengths of light by different amounts
The wavelengths that are the most strongly reflected determine the colour
what happens to the wavelength of light that aren’t reflected by an opaque object?
Any wave lengths that aren’t reflected absorbed by the object
what colour does an object appear if all wavelengths are reflected by equal amount?
White
what colour does an object appear if all wavelengths are absorbed?
Black
