waves Flashcards
two types of waves
- transverse
- longitudinal
what is a transverse wave
a wave for which the oscillations are perpendicular to the direction of energy transfer
what is a longitudinal wave?
a wave for which the oscillations are parallel to the direction of energy transfer
2 examples of transverse waves?
- electromagnetic waves
- seismic s-waves
2 examples of longitudinal waves
- sound waves
- seismic p-waves
what are two parts of a longitudinal waves called
compression and rarefactions
what is a wave amplitude
the maximum displacement of a point on a wave from its undisturbed position
what is wavelength?
the distance from a point on a wave to the same position on the adjacent wave
most commonly peak to peak to trough to trough
what is the frequency of a wave
the number of waves that pass a given point each second
what is the unit for frequency
Hz
what is wave speed
the speed at which the wave moves or at which energy is transferred through a medium
what does a wave transfer
energy
wave speed calculation
wave speed = frequency x wavelength
what word is used to describe when a wave bounces off a surface
reflection
how do sound waves travel through a solid
the particles in the solid vibrate and transfer 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
example of an use for ultrasound waves
medical or industrial imaging
what natural event causes seismic waves to be produced
earthquakes
they produce both p-waves and s-waves
state a 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 not liquids
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 emission and detection alongside wave speed and used to calculate distances
what type of spectrum do electromagnetic waves form
a continuous spectrum
order the types of electromagnetic radiation from lowest to highest frequency
- radiowaves
- microwaves
- infared
- visible light
- ultraviolet
- x-rays
- Gamma rays
how do the speeds of em radiation differ in a vacuum and in the air
electromagnetic waves all 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 denser materials cause refraction
in which direction do waves refract when entering a denser medium
the 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 an electrical circuit
radio waves
how can radio waves create an alternating 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 issues can ultravoilet light cause
they can cause the skin to age prematurely
increase the risk of developing skin cancer
what health effects can x-rays and gamma rays cause
they are ionising radiation so can cause mutations in genes
they can lead to increased risk of developing various cancers
give 3 practical uses for infrared radiation
- electrical heaters
- cooking food
- infrared cameras
give 2 practical uses for microwave radiation
- satellite communications
- cooking food
give 2 practical uses for radio waves
- tv transmission
- radio transmission
what wave phenomena 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 principle focus
what is the difference between the image produced by a convex and concave wave
convex lenses can produce real or virtual images
concave 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 of visible light has the highest frequency
blue
what colour of visible light has the largest wavelength
red
what is meant by the term specula 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 wavelengths of light other than those in the red range 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 amount
the wavelengths that are most strongly reflected determine the colour
what happens to the wavelengths of light that aren’t reflected by an opaque object
any wavelength that aren’t reflected are absorbed by the object
what colour does an object appear if all wavelengths are reflected by equal amounts
white
what colour does an object appear id all wavelengths are absorbed
black
what do all bodies emit and absorb
infrared radiation
what happens to the quantity of infrared radiation emitted by an object as temp increases
the hotter the object, the more infrared radiation it will emit
what is a perfect black body
huh
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 emitter of radiation
it is a perfect absorber since it absorbs all radiation incident on it
a perfect absorber is also a prefect emitter
other than the intensity of radiation emitted, how does increasing the temp of an object affect its emissions
the wavelength distribution of an emission is dependent on the objects temp
what can be said about the rates of emission and absorption for a body at constant temp
the body is absorbing and emitting radiation at the same rate
what can be said about the rates of emission and absorption for a body increasing in temp
the body is absorbing radiation faster than it is emitting it
give 2 facts that affect the temp of earth
the earths rate of absorption and emission of radiation
the amount of reflection of radiation into space
