waves Flashcards by nour waleed

what do waves transfer

energy

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what do mechanical waves travel through

a medium (matter)

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whatre all waves categorised into

transverse or longitudinal

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describe an give an example for transferse waves

they osciate perpendiculat to the direction of energy transfer. electromagnetic waves

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describe and give an example of longitudinal waves

they osscilate parallel to the direction of energy transfer, sound and water waves

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whats the equation to calculate wave speed

wavespeed=frequency x wavelength

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whatre compressions and rarefactions

in longitudinal waves
-compression is when the waves are close together
-rarefaction is when theyre spread lut

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what happens to waves at a boundary between 2 different matierials

theyre either
-reflected
-transmitted
-absorbed

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whats refraction

when waves change direction as they cross from 1 medium to another due to a change in velocity

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incident ray and incident angle =..

reflected ray and reflected angle

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whatre the 5 different ways to descrube wave motion

-frequency in Hz
-wavelentj
-period (1/f)
-amplitude
-wavefront

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whatre electromegnetic waves

transferve waves that tranfer energy from the source of thw wave to an absorber

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whats the wavespeed of all transferve waves

300 million m/s

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name all the waves in the electromegnetic spectrum

RAW MEAT IS VERY UNSANITARY EXCEPT GIRRAFES
-radio waves
-microwaves
-visible light
-ultraviolet
-xrays
-gamma rays

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what happens as you go across the spectrum

-wavelength decreases ans frequency increases

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whats meant by diffraction

the spreading out of waves as they apass through a gap or obsticle

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what happens to diffraction when the gap is narrow

the waves spread further away from the gap

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how do we see different visible light

its detected by our eyes in terms of wavelength

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all objects —- and —– infrared radiation

emmit and absorb

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what does the frequency and amount of emitted radiation depend on

the temp and surface of a given object
-hotter -> more radiaton emitted

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what 4 waves are used for communication

-microwaves
-radiowaves
-infrared
-visible light

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whats an optical fiber

thin and transparent fibers that transfer signals by either visible light or infrared radiation

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why are shorter radiowaves more useful in communications

because they can carry more info without a weakend signal and theyre more easily absorbed

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whatre the uses of radiowaves

-tv systems
-radio systems
-bluetooth

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whatre the uses of microwaevs

- mobile phones -satalites -microwave ovens (when waves are absorbed by water molecules)

whatre the uses of infrared rays

- tv remote controls -night vision devices -heating

whatre the uses of visible light

-optic fiber communications, photography

whatre ultraviolet rays used for and whyre they harmful

- security marking and sun beds -can cause skin cancer and blindness

whatre the issues with x rays gamma rays

are ionising -x rays can kill cells and gamma rays can cause genetic mutations

whatre the properties of x rays

-affect photographic films in the same ways as light -absorbed by metal and bones (dense) -stopped by lead -transmitted by healthy tissues

whatre the adv and disadvantages of ct scans

- adv: produce detailed 3d images differentiate between soft and hard tissue dis- expensive and give higher radiation doses

whatre the uses of gamma rays and what are the effects of large doses

- used to steralise medical equipment , kill harmful bacteria in food and kill cancer cells -can cause genetic mutations in large dosages

what type of waves are sound waves

longitudinal waves that travel through a medium

whats the frequency range of the human ear

20hz to 20,000 hz

how are echos created

by soundwaves being reflected by a smooth and hard surface

how are sound waves defracted

when they pass through a gap (ex-door)

what happens when the frequency of a sound wave increses

the pitch increases

what happens when the amplitude of a sound wave increases

the sound becomes louder

whys ultrasound scans (prenatal) safer than xrays

theyre nonionising and usually reflected

whatre ultrasound waves

sound energy with a frequency above human hearing (over 20,000 hz)

how can u calculate the distance between different mediums

distance = wavespeed x time

whatre the uses of ultrasound waves

ultrasound scans in medicine (prenatal scans) destroying kidney stones

whats a plane mirror

a perfectly flat mirror

whats the law of reflection

in a plane mirror, angle of incidence is equal to the angle of reflection

whatre angles of incidence,reflection and refraction always measured between

the ray and the normal

whatre the features of.a virtual image

virtual and upsright,cant be projected onto a screen

why can real images be shown on a screen

because all the different light rays are fo used directly onto the screen

whats meant by the refraction of light

the change in direction of light rays when traveling across a boundary from 1 medium to another

what happens when light rays travel from air to glass

the incident ray anglr is greater than the reflected ray angle and light rays bend towards the normal

what happens when light rays travel from glass to air (less dense medium)

reflected angle is greater than the incident angle and the light ray is reflected away from the normal

whats the 1 case wwhere the velocity of wave doesnt change when entering a difff medium

if it enters at 90 degrees (along the normal)

what happens when light is refracted by a prism

a dispersion of light waves and the formation of a spectrum

whats the refractive index

in terms of wavspeed, speed of light in vaccum/speed of light in medium

what does the refractive index measure

how much a medium can reflect a light ray

whats the law of reflection

n(refractive index) = sin i(incident angke)/sin r (refracted angle)

whats the relationship between the refractive index and the critical angle

n= 1/sinc

whats total internal reflection and when can it occur

in a dense to less dense medium. if angle of incidence is greater than the critical angle.

what type of images do convex lenses produce

real image (lines meet)

how do you describe an image

- upright or inverted -real or virtual -magnified or dimminished

what type of image does concave lenses form

virtual

how do you calculate magnification size

image height/object hieght

whats the job of the retina

to focus images

whats the job of the cillary muscles

they alter thickness of an eye lens and are attached by the suspensory ligaments

what 2 strcutures refract light entering the cornea

cornea and lens

whats the near point of the human eye

25 cm

what lenses are used to correct short signtedness

concave (diverging)

whar lenses are used to correct long signtedness

convex (converging lenses)

how are lases used

in eye surgery to correct visual defects

whats the equivilant of film in cameras

the retina in the eye