waves Flashcards
what are waves produced by
oscillating or a vibrating system
what are oscillation and vibration
repetitive motions about an equilibrium in a closed path
what are progressive waves
is a wave that travels with time along the direction of propagation of the wave
what are stationary waves
a wave where the profile of the wave does not propagate with time
how can stationary waves be produced
through musical instruments such as guitars
list 3 points for mechanical waves
requires medium to transfer energy from one point to another
made up of vibrating particles of a medium
water waves, sound waves, and seismic waves on the surface of the earth are mechanical waves
list 3 points for electromagnetic waves
does not require a medium
made up if oscillating electric and magnetic fields perpendicular to one another
radio waves, light waves and gamma rays are examples of them
compare transverse waves and longitudinal waves
particles of the medium vibrate in the direction perpendicular to the direction of the propagation of the wave
particles of the medium vibrate in the direction parallel to the direction of propagation of the wave
made up of crests and troughs
made up of consecutive compressions and rarefactions
what is the definition of amplitude, A
maximum displacement of a particle from its equilibrium position
what is the definition of period, T
the time taken by a particle to make one complete oscillation or by a source to produce one complete cycle of wave
what is the definition of frequency, f
number of complete oscillations made by a particle or number of cycles of waves produced by a source in one second
what is the definition of wavelength, lambda
distance between two consecutive points in phase
what is the definition of wave speed, v
distance travelled per second by a wave profile
what is the formula for speed of wave
v = f lambda
sketch the graph of displacement against time and distance for waves
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what are the two dippers used in ripple tank
plane dipper and spherical dipper
how does oscillating systems experience energy loss
external damping
loses energy to overcome friction to sir resistance
internal damping
loses energy because stretching and compression if the vibrating particles in the system
what is damping
damping is the reduction in amplitude in an oscillating system due to loss of energy.
during damping, the oscillating frequency remains constant while the oscillating amplitude decreases.
how can the effect of damping be overcome
applying periodic external force on the oscillating system. the periodic external force transfers energy into the oscillating system to replace the energy lost.
the system is said to be in forced oscillation
how does an oscillating system be at resonance
when a periodic force is applied to an oscillating system at its natural frequency
what happens during resonance
the system oscillates with its natural frequency
system oscillates with maximum amplitude
what is wavefront
a surface over in which the wave is constant
what happens to angle of incidence and angle of reflection when wave is reflected
angle of incidence = angle reflection
what happens to the wavelength after reflection of wave
no change
what happens to the frequency when wave is reflected
no change
what happens to the direction of propagation when wave is reflected
changes with the condition that the angle of incidence is the same as angle of reflection
try to draw the diagram for reflection of water waves
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give 4 applications of reflection of waves in daily life
ultrasonic waves
used in medical field to examine a foetus or other internal organs
radio waves
from communication satellites are reflected by the parabolic dish and focussed into the antenna in the feed horn
technology of ultrasonic of reflection
which is known as sonar helps to detect areas which have a lot of fish. transducer transmit waves into the water and these waves are reflected by the fish to the transducer
patterns of reflected sound waves caused by different rocks
enable the location, depth and structure of the sea bed which contain sources if natural gas to be identified
solve problem involving reflected waves
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what does refraction of waves mean
the change in direction if propagation of waves caused by the change in the velocity of waves when the waves propagate from one medium to another
what influence speed of water waves
depth of water
what influence speed of sound waves
density of air
what influence speed of light wave
optical density if medium
what happens to the angle of incidence and angle of refraction when waves move from deep water region to shallow water region
angle of incidence > angle of refraction
what happens to the angle of incidence and angle of refraction when waves move from shallow water region to deep water region
angle of incidence < angle refraction
what happens to the wavelength when waves move from deep water region to shallow water region
decreasing
what happens to the wavelength when waves move from shallow water to deep water region
increasing
what happens to the frequency when waves move from deep water region to shallow water region
no change
what happens to the frequency when waves move from shallow water region to deep water region
no change
what happens to the wave speed when waves move from deep water region to shallow water region
decreasing
what happens to the wave speed when waves move from shallow water region to deep water region
increasing
what happens to the direction if propagation when waves move from deep water region to shallow water region
reflected towards the normal
what happens to the direction of propagation when waves move from deep water region to shallow water region
reflected away from the normal
try to draw the diagram for the refraction of plane water waves
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why cant an observer hear clearly during daytime
air that is closer to the surface of the earth is hotter than the air above
sound moves faster in hot air than in cold air. as such, sound reflected away from the ground
thus, an observer cant hear clearly during the day
why can an observer hear more clearly during the night
during the night, air that is closer to the surface of the earth is colder. Sound is refracted towards the ground.
why the amplitude of waves at bay is smaller that at the cape
the cape is the shallow water region while the bay is the deep water region. Away from the shoreline, the wavefront of the water is almost straight and parallel because water waves move at a uniform speed.
when the wavefront of the water propagates to the cape, the speed of the water waves decreases causing the wavelength to be shorter. Wavefront of water approaching the bay moves at a higher speed and the wavelength is longer. This causes the wavefront to curve and follow the shape of the shoreline.
refraction of water waves causes water wave energy to converge towards the cape. Water wave energy diverges from the bay and spread out to a wider region. Thus, the amplitude of waves at bay is smaller than at the cape.
what is refraction of waves caused by
the change is speed of waves
what is the formula of speed of wave
v= f lambda
what is the formula for deep and shallow region for refraction of waves
v/lambda = v/lambda
what does diffraction of waves mean
is the spreading of waves when the waves propagate through a slit or side of a barrier.
what changes to the wave will occur when diffraction occur
amplitude, direction of propagation
what happens to the amplitude when diffraction of waves occur
decreased, wave energy diverges and spread out to a wider region
what happens to the direction of propagation when diffraction of waves occur
from one direction to many, wavefront spreads
draw the pattern of diffraction for wide slit
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draw the pattern of diffraction for narrow slit
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draw the pattern of diffraction for short wavelength
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draw the pattern of diffraction for long wavelength
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what is diffraction of waves influenced by?
size of slit and wavelength
give 3 examples for the diffraction of waves in daily life
water waves,
diffraction of water waves produces calm of water regions suitable for docking of ships and water recreational activities.
light waves,
holograms produced by effects of diffraction of light are used as safety features on bank cards such as debit cards and credit cards.
sound waves
infrasonic waves produced by elephants have long wavelength to facilitate ling distance communication between elephants
what is the meaning of interference of waves
is the superposition of two or more waves from a coherent source of waves
how are two waves coherent
when the frequency of both waves is the same and the phase difference is constant.
what does superposition of waves produces
constructive interference
destructive interference
how does constructive interference occurs
when two crests are in superposition
when two troughs are in superposition
how does destructive interference occur
when a crest and a trough are in superposition to produce zero combined displacement
how do you identify constructive interference in ripple tank
bright and dark area
how do you identify destructive interference in ripple tank
grey area
how do you identify constructive and destructive interference in interference of light waves
constructive interference produce bright fringe while destructive interference produce dark fringe
how do you identify constructive and destructive interference in interference of sound waves
loud sound = constructive interference
soft sound = destructive interference
identify destructive and constructive interference from sketch
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what is the formula for interference of waves
lambda = ax/D
give 3 examples for applications of interference of waves in daily life
bulbous bow
coating on the surface of anti-reflection lens
microphone and transmitter system
HISTORY OF ELECTROMAGNETIC WAVES
what did thomas young discovered in 1801
light is a wave through experiments on interference of light
HISTORY OF ELECTROMAGNETIC WAVES
what did james maxwell discovered in 1862
put forth the theory that light is an electromagnetic wave.
HISTORY OF ELECTROMAGNETIC WAVES
what did heinrich hertz discovered in 1887
generated a different kind of electromagnetic wave, that is radio wave
HISTORY OF ELECTROMAGNETIC WAVES
what did is the discovered in early 20th century
electromagnetic waves are made up of:
- gamma ray
- x-ray
- ultraviolet ray
- visible light
- infrared ray
- microwave
- radiowave
what are electromagnetic waves made up of
electric field and magnetic field that oscillate perpendicularly to one another
draw the electromagnetic spectrum that shows the frequency and wavelength of rays
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how is radio wave used
long distance radio communication
local radio and tv broadcasting
wireless communication
millimetre-wave machine to scan body of passengers at airport
how is microwave wave used
international communication through use of satellite
mobile phone framework
communication between electronic devices: wifi, bluetooth,
detection of plane radar and speed trap
cooking
how is infrared ray used
enable living things to see
photography
photosynthesis in green plants
laser light used in cutting of metal, measurement of land and sending of information through optical fibres.
how is ultraviolet ray used
harden tooth filling material
determines authenticity of currency notes
treatment of jaundice in babies
purification of drinking water
sterilising surgical instruments and food
insect traps
how is x-ray used
detects fractures or broken bones and examines internal organs
checking of welding connections
baggage scanning at airport
determine authenticity of paintings
how is gamma ray used
kills cancer cells in radiotherapy
sterilisation of surgical and medical equipment is bulk
used in food processing industry so that food can last longer
