Chapter 11&12: Waves

Question 1

define displacement

Answer 1

how far away an object is from its origin

Question 2

define amplitude

Answer 2

the maximum extent of a vibration or oscillation measured from the position of equilibrium

Question 3

define wavelength

Answer 3

distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave

Question 4

define time period

Answer 4

interval of time between successive occurrences of the same state in an oscillation

Question 5

time period equation

Answer 5

T = 1/f

Question 6

define frequency

Answer 6

how often a wave occurs

Question 7

frequency equation

Answer 7

f = 1/T

Question 8

define wave speed

Answer 8

how fast a wave travels

Question 9

wave speed equation

Answer 9

v = f x λ

Question 10

what is phase difference

Answer 10

the fraction of an oscillation between two oscillating

Question 11

what is reflection

Answer 11

when a wave changes direction at a boundary between two different media, remaining in the original medium

Question 12

what is refraction

Answer 12

when a wave changes direction as it changes speed when passing from one medium to another

Question 13

what is the reflection rule

Answer 13

angle of incidence = angle of reflection

Question 14

what is diffraction

Answer 14

spreading of a wave when i passes through a narrow gap or around an obstacle

Question 15

what is a plane polarised wave

Answer 15

wave with oscillations in one plane only

Question 16

what is intensity

Answer 16

radiant power passing perpendicular through a surface per unit area

Question 17

what is the intensity equation

Answer 17

I = P/A
I - relating intensity
P - incident radiant power
A - area

Question 18

what is a wavefront

Answer 18

lines which show points on waves that are in phase

Question 19

what are electromagnetic waves

Answer 19

transverse waves whose oscillations are changes in electrical and magnetic fields and are perpendicular to direction of travel

Question 20

what are the three properties of EM waves

Answer 20

> transfer energy as radiation
travel through a vacuum
travel through vacuum at 300 000 000 ms-1

Question 21

what are the seven EM waves

Answer 21

radiowaves
microwaves
infrared
visible light
ultraviolet
X-rays
gamma rays

Question 22

what are the properties of radiowaves

Answer 22

longest wavelength
lowest frequency
lowest energy level

Question 23

what are the uses of radiowaves

Answer 23

used in TV and radio communication because easily transmit through air and dont cause damage to humans

Question 24

describe microwaves

Answer 24

second longest waves used in cooking because they increase the internal energy of molecules heating them
they are also used in satellite communication because they can pass through atmosphere

Question 25

describe infrared

Answer 25

used in cookers because when absorbed they increase the internal bond energy cause heating

Question 26

describe visible light

Answer 26

different frequencies within the range cause the different colours used in fibre optic cables which transmit data

Question 27

describe ultraviolet

Answer 27

these waves are emitted by the sun and cause the skin to tan and burn

Question 28

describe x-rays

Answer 28

these are the second shortest EM waves and our absorbed by dense materials such as bones but transmit through less dense materiel such as skin creating an internal body image

Question 29

describe gamma rays

Answer 29

the shortest and highest energy waves so are radioactive but work similarly to x-rays so used as medical tracers in the body

Question 30

what is the refractive index of light equation

Answer 30

n = c / v

refractive index = speed of light through a vacuum / speed of light through the material

Question 31

what is snells law

Answer 31

n1sinθ1 = n2sinθ2