4.4

Question 1

amplitude

Answer 1

maximum displacement of a wave from its rest position

Question 2

ferquency

Answer 2

number of complete wave cycles that occur in one second

Question 3

period

Answer 3

time taken for a wave peak to travel the distance of one wavelength(time taken for one oscillation)

Question 4

progressive wave

Answer 4

a type of wave that travels through a substance or space

Question 5

transverse wave

Answer 5

type of wave in which oscillations occurs at rights angles to the direction of wave propagation

Question 6

longitudinal wave

Answer 6

a type of wave in which oscillations occur parallel to the direction of wave propagation (cant travel through a vacuum).

Question 7

what is path difference measured in

Answer 7

n λ (1 λ= 1 wavelength)

Question 8

what is phase difference measured in

Answer 8

π radians (2πvradians = 1λ)

Question 9

principal of superposition

Answer 9

when 2 or more waves meet the total displacement at any one point is equal to the sum of the displacements that each individual wave would cause

Question 10

interference

Answer 10

when two waves interact with each other

Question 11

coherence

Answer 11

when waves have constant phase difference

Question 12

constructive interference occurs when

Answer 12

the path difference between coherent sources is nλ where n is an integer

Question 13

cancellation occurs when

Answer 13

the path difference between two coherent sources is nλ/2

Question 14

stationary/ standing wave

Answer 14

the superposition of two progressive waves with the same wavelength moving in opposite directions energy is stored

Question 15

node

Answer 15

point on a stationary wave where no displacement occurs

Question 16

anti node

Answer 16

point of a stationary wave where maximum displacement occurs

Question 17

em spectrum

Answer 17

radio, microwaves, visible light, uv, x-rays, gamma

Question 18

physical waves

Answer 18

progressive waves that transfer matter/particles ie sound waves or water waves

Question 19

electromagnetic waves

Answer 19

progressive waves that transfer energy without transferring matter

Question 20

properties of em waves

Answer 20

can travel through a vacuum, posses both a magnetic and electrical waves at right angles to each other, all travel at 2.98x10^8 m/s in a vacuum, all transverse, all can be reflected refracted and diffracted, all demonstrate interference, all can be polarized

Question 21

polarized wave

Answer 21

a plane polarized wave oscillates in only one plane happens only in transverse waves

Question 22

what are polarizing filters made of

Answer 22

crystalline materials that absorb waves

Question 23

applications of polarized light

Answer 23

tv signals and radio signals are polarized so transmitting and receiving aerials must be aligned, 3d glasses, stress analysis of plastic

Question 24

malus’s law

Answer 24

the light passing through a perfect polarizer can be found by the equation= I=Imaxcos^2θ

Question 25

refraction

Answer 25

the change in direction a light ray undergoes when it enters a medium with a different optical density

Question 26

why does refraction occur

Answer 26

light travels at different speeds in materials with different optical densities. the change in direction occurs due to the change in speed

Question 27

in what direction does light bend

Answer 27

towards the normal as it slows, away from the normal as it speeds up

Question 28

how to find the refractive index of a material

Answer 28

n=c/v

Question 29

snells law

Answer 29

n1sin1 θ1=n2sin2 θ2

Question 30

critical angle

Answer 30

when the angle of incidence = the critical angle light will travel along the boundary of the secondary medium it will be refracted by 90 degrees

Question 31

total internal reflection

Answer 31

when the angle of incidence exceeds the critical angle light is reflected in the material

Question 32

young's double slit equation

Answer 32

λ=(ax)/d d=distance from slits to screen, x=distance between adjacent maxima, a=slit sepparation

Question 33

diffraction

Answer 33

the spreading out/bending of light waves as they pass through a gap or around an obstacle

Question 34

when is diffraction greatest

Answer 34

when the width of the aperture=wavelegnth

Question 35

diffraction grating

Answer 35

a place with many closely spaced parallel slits that produces spaces interference pasterns as a result of superposition

Question 36

why use diffraction gratings not a double slit arangement

Answer 36

the pattern is much clearer making it possible to calculate the wavelength

Question 37

diffraction grating equation

Answer 37

nλ=dsinθ d=slit sepparation

Question 38

how to find the maximum number of orders

Answer 38

substitute θ=90

Question 39

Fundamental mode of vibration

Answer 39

In this mode the length of the string is 1/2 the wavelength. This produces the lowers possible frequency the 1st harmonic

Question 40

2 ways to graph waves

Answer 40

* "snapshot of wave" shows displacement (y axis) vs distance travels (x axis) * displacement against time

Question 41

How to represent longitudinal waves graphically

Answer 41

Pressure against position

Question 42

How to find the period of a wave with an oscilloscope

Answer 42

Distance between peaks x time base setting

Question 43

Uv-a

Answer 43

99% of uv Causes tanning 3.15-4 x10-7 meters (wavelength)

Question 44

Uv-b

Answer 44

Causes skin cancer and sunburn | 2.8-3.15x10-7 m wavelength

Question 45

Uv-c

Answer 45

Filtered out by atmosphere | 1-2.8x10-7 m wavelength