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Flashcards in paper 2 : waves Deck (49)
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1

what does a wave transfer

waves transfer energy without transferring matter

2

what are the 2 types of waves

the 2 types of waves are:
-longitudinal
-transverse

3

give some examples of longitudinal and transverse waves

some examples of longitudinal and transverse waves are :
-longitudinal = sound and seismic push waves
-transverse waves = all electromagnetic waves and seismic shake waves

4

what is meant by the 'frequency' of a wave

the frequency of a wave is the number of waves passing a point each second

5

how can you calculate the frequency of a wave

you can calculate the frequency of a wave by using this equation :
period = 1/frequency

6

what is frequency measured in

frequency is measured in hertz, Hz

7

what is meant by 'period'

a period is simply the time taken to complete 1 complete wave

8

what is the speed of sound in air

the speed of sound in air is 334m/s

9

what is the speed of light and all electromagnetic waves

the speed of light and all electromagnetic waves is 3x 10^8 m/s

10

what happens to wave speed in a constant medium

in a constant medium(the same substance), wave speed stays the same

11

what is the range for normal human hearing

the range for normal human hearing is 20Hz to 20KHz

12

why are there restrictions to human hearing

there are restrictions to human hearing as the conversion of sound waves to vibrations of the solid, works over a limited frequency range

13

describe the effect of sound waves on the ear drum

sound waves affect the ear drum by:
-differing pressures outside and inside the ear drum causes the ear drum to move
-the differing pressures are caused by the compressions and rare-fractions of longitudinal sound waves on the outside of the ear
-if the pressure is increasing, force in the ear must also increase as pressure is ∝ to force (F=pxA)
-as the area inside and outside the ear is the same, a greater force on the outside of the ear compared to the one in the ear, will cause the ear drum to move inwards and vice versa

14

what are rare-fractions

rare-fractions are when the waves are furthest apart

15

what is the angle of incidence

the angle of incidence is the angle at which the ray reflects at

16

what can happen when a wave passes through a boundary(the end of a material and the start of a new one)

at a boundary waves can be either :
-reflected
-absorbed
-transmitted without refraction
-transmitted with refraction

17

what is refraction

refraction is when light rays bend towards the normal when they enter a new material

18

how can ultrasounds be used for medical imagery

ultrasounds are used for medical imagery as :
-at the boundary between 2 different media (air and skin), the ultrasound waves are partially reflected
-doctors can then determine how far away each boundary is by recording the time taken for the reflections to reach the detector

19

what are 2 uses of ultrasounds

2 uses of ultrasounds are :
-unborn baby scans
-measuring the speed of blood flow in a vein or artery

20

why is a gel used in baby ultrasounds

a gel used in baby ultrasounds as it prevents from all the waves being reflected: the gel balances the difference between the 2 medias

21

list the types of electromagnetic waves in order of wave length (biggest to smallest)

the types of electromagnetic waves in order of wave length (biggest to smallest) are :
-radio waves
-microwaves
-infrared
-visible
-ultraviolet
-X-rays
-gamma

22

list the types of electromagnetic waves in order of frequency (smallest to biggest)

the types of electromagnetic waves in order of frequency (smallest to biggest) are :
-radio waves
-microwaves
-infrared
-visible
-ultraviolet
-X-rays
-gamma -

23

how does the speed of a wave change if was to enter a block

the speed of a wave in the block would be slower than the speed of the wave in air

24

what is the principal focus (F on a ray diagram)

the principal focus is where all the fays of light are brought to focus

25

what is the focal length

the focal length is the distance between the lens and the principal focus

26

what do concave and convex lens' do to light rays

concave lens cause light rays to diverge
convex lens cause light rays to converge

27

what type of image will a concave or a convex lens produce

a concave lens will always produce a virtual image
a convex lens will always create a virtual or real image

28

what is specular reflection

specular reflection is when reflection occurs from a smooth surface in one direction

29

what is diffuse reflection

diffuse reflection is when reflection on a rough surface causes scattering

30

how do colour filters work

colour filters work by absorbing certain wave lengths and colours and transmitting others