waves

Question 1

longitudinal

Answer 1

oscillations parallel to direction of energy transfer
sound

Question 2

transverse

Answer 2

oscillations perpendicular to direction of energy transfer
light, water

Question 3

waves transfer…

Answer 3

energy not matter

Question 4

amplitude A

Answer 4

distance between rest positions and peak/trough
sound = loudness
light = brightness

Question 5

wavelength

Answer 5

distance between two identical points on a wave (m)

Question 6

frequency f

Answer 6

no. complete waves per second Hz
sound = pitch
light = colour

Question 7

time period T

Answer 7

time for one complete oscillation (secs)

Question 8

frequency and time period

Answer 8

f = 1/T

Question 9

velocity v

Answer 9

speed of wave m/s

Question 10

velocity formula

Answer 10

v= d/t
v = wavelength/ T
v = f x wavelength

Question 11

peak

Answer 11

highest point on wave

Question 12

trough

Answer 12

lowest point on the wave

Question 13

mechanical wave

Answer 13

transfers energy by the vibration of particles - so can’t travel in a vacuum
sound

Question 14

speed of sound depends on

Answer 14

the medium - where particles are close vibrations get passed on quickest

Question 15

sounds with freq. above 20kHz

Answer 15

ultrasound

Question 16

range of human hearing

Answer 16

20 - 20 000 Hz

Question 17

experiment to measure speed of sound in air

Answer 17

• measure distance to walk
• person1 claps person2 starts stop clock
• person2 stops timing when they hear echo
• use s=d/t
• repeat and average

Question 18

how boats use ultrasound

Answer 18

use for echolocation
use to see how far things are
- time between sending and receiving pulse recorded
- speed of sound know
use d = s x t/2 to find d

Question 19

speed of sound in air

Answer 19

330 m/s

Question 20

ultrasound uses

Answer 20

• imaging foetus
• shattering kidney stones
• clean delicate mechanisms without dismantling them

Question 21

CRO traces

Answer 21

• set controls so complete wave is on the screen
• amplitude = count squares x volts/div
• time period = squares for one full wave x time base
• freq. = 1/T

Question 22

oscilloscopes

Answer 22

instrument that portrays waves as traces of light on a screen

Question 23

signal generator

Answer 23

used with loudspeaker and amplifier to make sounds of large freq. range

Question 24

similarities between waves in emag. spectrum

Answer 24

• transverse
• travel in vacuum
• travel at speed of light (3x10^8m/s)
• undergo interference (reflect, refract etc.)

Question 25

longest wavelength wave

Answer 25

radio waves

Question 26

shortest wavelength wave

Answer 26

gamma rays

Question 27

lowest freq. wave

Answer 27

radio

Question 28

highest freq. wave

Answer 28

gamma rays

Question 29

emag. spectrum

Answer 29

- radio waves - microwaves - infrared - visible light - ultraviolet - x-rays - gamma rays

Question 30

gamma ray uses

Answer 30

treating cancer sterilisation

Question 31

x-ray uses

Answer 31

medical imaging airport security

Question 32

UV uses

Answer 32

security marking fluorescent tubes

Question 33

visible light uses

Answer 33

seeing photograoht

Question 34

infrared uses

Answer 34

heaters night vision equipment

Question 35

microwave uses

Answer 35

cooking satellite transmissions

Question 36

radio wave uses

Answer 36

communications

Question 37

gamma ray dangers

Answer 37

mutation cancer kill living cells (ionising radiation)

Question 38

xray dangers

Answer 38

cancer cell damage

Question 39

uv dangers

Answer 39

blindness cancer suburn

Question 40

visible light dangers

Answer 40

damage eyes

Question 41

infrared dangers

Answer 41

burning of tissues (heat

Question 42

microwave dangers

Answer 42

heats water within body damage cells

Question 43

radio wave dangers

Answer 43

none

Question 44

law of reflection

Answer 44

angle of incidence is = to angle of reflection i= r

Question 45

normal line

Answer 45

line perpendicular to a surface

Question 46

refraction

Answer 46

when light changes speed and or direction when it passes from one medium to another of diff. density

Question 47

light speeds

Answer 47

away from normal

Question 48

light slows

Answer 48

toward normal

Question 49

light hits surface at 0° to normal

Answer 49

no directionchabge

Question 50

light bends if

Answer 50

it’s incident at an angke

Question 51

experiment to measure refractive index of glass

Answer 51

- trace glass block - shine light from ray box into glass block - mark ray of light in pencil - remove block and draw normal line - measure angle of incidence and reflection with protractor - repeat several value did i plot graph of sin i (y) and sin r (x) - gradient is refractive index

Question 52

refractive index

Answer 52

measure of the light bending ability of a medium n = sin i / sin r - only light slowing down

Question 53

TIR

Answer 53

total internal reflection - when an angle of incidence is great enough light bends so far away it goes back inside - if i>C TIR occurs

Question 54

critical angle

Answer 54

greatest angle at which a ray can travel through and be refracted without TIR occurring sinC = 1/n

Question 55

uses of TIR

Answer 55

- transmit info quickly in high speed internet - used in endoscopes in keyhole surgery - along optical fibres + prisms + periscopes