11.1 - 11.9

Question 1

define progressive wave

Answer 1

a wave that transfers energy, but not matter, through a medium

Question 2

define Transverse wave

Answer 2

a wave in which the particles in the medium oscillate perpendicular to the direction of energy transfer

Question 3

define longitudinal wave

Answer 3

a wave in which the particles in the medium oscillate parallel to the direction of energy transfer

Question 4

examples of transverse waves

Answer 4

EM waves,

S- waves

Question 5

examples of longitudinal waves

Answer 5

sound waves,

P- waves

Question 6

what’s the range of human hearing

Answer 6

20 - 20k Hz

Question 7

define displacement

Answer 7

distance from the equilibrium position in a particular direction

Question 8

define amplitude

Answer 8

maximum displacement from the equilibrium position

Question 9

define wavelength

Answer 9

the minimum distance between two points oscillating in phase

Question 10

define wave period

Answer 10

the time taken for a wave to complete one oscillation

Question 11

define frequency

Answer 11

the number of wavelengths that can pass a single point per unit time

Question 12

define wave speed

Answer 12

the distance travelled per unit time

Question 13

define phase difference

Answer 13

the difference between the displacements of particles along a wave or on different waves. measured in degrees or radians

Question 14

define the term ‘antiphase’

Answer 14

when particles along a wave have a phase difference of 180 degrees

Question 15

why are longitudinal waves faster in a solid?

Answer 15

the particles are closer together so the transfer of energy is faster.

Question 16

define reflection

Answer 16

when a wave changes direction at the boundary between two different media and remains in the original medium

Question 17

what is the law of reflection

Answer 17

the angle of incidence equals the angle of reflection

Question 18

what is the angle of incidence/reflection

Answer 18

the angle between the normal and the ray of incidence/reflection

Question 19

define refraction

Answer 19

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

Question 20

what does refraction change about a wave

Answer 20

the speed and wavelength. it can not change the frequency

Question 21

define diffraction

Answer 21

when waves pass through a gap or around an object they spread out. The speed, wavelength and frequency of diffracted waves remain the same.

Question 22

what affects diffraction

Answer 22

the size of the wavelength compared to the size of the gap. if they are similar then diffraction is most significant.

Question 23

define polarisation

Answer 23

when the oscillations of a transverse wave are limited to one plane

Question 24

what is a plane polarised wave

Answer 24

a transverse wave which has its oscillations limited to a single plane

Question 25

why can't longitudinal waves be polarised

Answer 25

their oscillations happen parallel to the direction of energy transfer which means they are already limited to one plane

Question 26

define 'partially polarised'

Answer 26

when there are more oscillations in one particular plane but the wave is not completely polarised

Question 27

define wave intensity

Answer 27

the power passing through a surface per unit area

Question 28

how are wave intensity and distance from the source linked

Answer 28

intensity is inversely proportional to the distance from the source^2

Question 29

how are wave intensity and amplitude linked

Answer 29

intensity is directly proportional to the amplitude^2

Question 30

which end of the EM spectrum has the highest frequency

Answer 30

Gamma

Question 31

why can gamma rays and X-rays have the same wavelength

Answer 31

the type of wave is not determined by the wavelength. it's determined by the source.

Question 32

whats the wavelength range of each type of EM Wave in meters

Answer 32

``` Gamma- >10^-16 X-ray- 10^-8 to 10^-13 UV- 4*10^-7 to 10^-8 VL- 400-700nm IR- 7*10^-7 to 10^-3 Microwave- 10^-3 to 0.1 Radiowave- <10^6 ```

Question 33

what is a use of polarised waves?

Answer 33

communication transmitters. a horizontally and a vertically polarised wave will have minimal interference with each other

Question 34

what is a refractive index

Answer 34

the ratio of the speed of light in a material to the speed of light in a vacuum

Question 35

define total internal reflection

Answer 35

the reflection of all light hitting the boundary between two media, back into the original medium. the original medium must have a higher refractive index and the angle of reflection must be greater than the critical angle

Question 36

define critical angle

Answer 36

the angle of incidence between two media that will cause an angle of refraction to be 90 degrees.