physics

Question 1

what is a transverse wave

Answer 1

particles that oscillate perpendicular to the direction of the wave. There is no horizontal movement.

Question 2

what is a longitudinal wave

Answer 2

particles that oscillate parallel to the direction of the wave. there is no vertical movement.

Question 3

what is the peak

Answer 3

the point of maximum positive displacement

Question 4

what is the trough

Answer 4

the point of maximum negative displacement

Question 5

what is equilibrium

Answer 5

the point at which particles remain where there is no disturbance

Question 6

what is the amplitude

Answer 6

the difference between the max and the equalibrium

Question 7

what is the wavelength

Answer 7

one point of a wave to the identical point on the next wave

Question 8

what are examples of transverse waves

Answer 8

EM waves
String waves
water waves
S waves

Question 9

what are examples of longitudinal waves

Answer 9

sound

P waves

Question 10

what is frequency

Answer 10

the number of waves passing a point per second

Question 11

what is period

Answer 11

time taken to produce one complete wave

Question 12

what is the formula for velocity/ wavespeed

Answer 12

V= Fx Lamda 
wavespeed= frequency x wavelength

Question 13

what is the EM spectrum in order from shortest wavelength to longest wavelength

Answer 13

gamma ray
x ray
UV
visible light
infrared
microwave
radio

Question 14

what is the formula for period

Answer 14

1/ frequency

Question 15

when is there no phase difference

Answer 15

when 2 waves run along the same way at the same point will form one wave (they have the same peak and trough)

Question 16

when is there a phase difference

Answer 16

the fraction of a complete cycle between 2 points on a wave

Question 17

what is reflection

Answer 17

when waves hit a barrier/ boundary that they cant pass through, they are reflected.

Question 18

what is superposition

Answer 18

when 2 or more waves overlap, the displacement at a point is equal to the sum of the individual displacements at the point

Question 19

what is constructive inference

Answer 19

if both waves the same displacement/ in phase

wave 1+ 2= wave 3

Question 20

what is destructive inference

Answer 20

when waves are 180 degrees out of phase
if one wave has a positive displacement and the other has a negative
wave 1-2= wave 3

Question 21

what is a stationary wave

Answer 21

when 2 progressive waves of the same frequency travel in opposite directions, a stationary wave is produced

Question 22

what is an antinode

Answer 22

when the maximum displacement occurs

Question 23

what is a node

Answer 23

when no displacement occurs

Question 24

what is the EM spectrum from the longest wavelength to shortest

Answer 24

radio wave
microwave
infrared
visible light
visible light
UV
x rays
gamma rays

Question 25

why are lasers used as a light source

Answer 25

MONOCHROMATIC- emitted with only one wavelength COHERENT- all waves are either exactly in phase or display a constant phase difference COLLIMATED- a narrow, approximately parallel beam

Question 26

what is refraction

Answer 26

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

Question 27

what happens when a light ray enters a medium that is more optically dense

Answer 27

it slows down and bends towards the normal

Question 28

what happens when a light ray enters a medium that is less optically dense

Answer 28

it speeds up and bents away the normal

Question 29

what is the formula for incident ray and refracted ray

Answer 29

I1= R2

Question 30

what is the formula for refractive index

Answer 30

refractive index of a substance (n) = speed of light in the vacuum (c) / speed of light in a substance (v) OR sin R (angle of refraction)/ sin I (angle of incidence)

Question 31

what are optical fibres used for

Answer 31

used to send light signals from one place to another eg cable TV

Question 32

how do optical fibres work

Answer 32

light from a source is directed into a narrow glass fibre | the ray will undergo a series of total internal reflection each time it works

Question 33

what are the improvements made on the optical fibre

Answer 33

to wrap the core fibre in a material called cladding the cladding protects the core from scratches/ moisture that may enable light to leak out this allows info to be transmitted with a greater degree of security

Question 34

what other ways do we use optical fibres other than in communication

Answer 34

endoscopes contain 2 bundles of fibres, one is used to light the inside of the person while the other is used to bring back info

Question 35

what are the types of signal transmissions

Answer 35

analogue signal and digital signal

Question 36

what is an analogue signal

Answer 36

varies continuously in frequency and amplitude eg speech and FM radio

Question 37

what is a digital signal

Answer 37

has only 2 states (on and off) it is transmitted as a series of electrical or optical pulses. eg electrical pluses in cables, infrared pulses in optical fibres

Question 38

what is an emission spectra

Answer 38

the range of frequencies of light emitted by an element is produced by an element due to energy level changes of electrons the electrons lose energy when returning to a lower energy level they emit light of a specific frequency

Question 39

what is the speed (in instruments)

Answer 39

velocity of a wave on a string= tension in the string/ the mass per unit length of a string

Question 40

what are the advantages of digital signals

Answer 40

they are less affected by noise and have less energy loss and can travel further

Question 41

what are microwaves used for

Answer 41

mobile phone networks because their high frequency gives greater bandwidth which allows large amounts of data to be transmitted

Question 42

why are microwaves good

Answer 42

there is little to no interference because they can be divided into separate channels

Question 43

what is the quality of a signal affected by

Answer 43

wet weather as microwaves are strongly absorbed by water

Question 44

what is satellite communication

Answer 44

the signals are high power and are transmitted over long distances radio waves are reflected by the ionosphere and so it can be used for terrestrial communication

Question 45

what are infrared communications

Answer 45

used in low power devices such as remote controls operates over a short distance and in line of sight doesnt work well in bright sunlight