P5.1 - Wave Behaviour

Question 1

What is a wave?

Answer 1

an oscillation that transfers energy (without transferring matter)

Question 2

how are sound waves produced?

Answer 2

when vibrations in your vocal cords produce sound waves

Question 3

How do phones communicate ?

Answer 3

Using Electromagnetic waves

Question 4

define amplitude

Answer 4

the maximum displacement of a point of a wave from its rest position

Question 5

Define Wavelength

Answer 5

distance from one peak (or trough) to the next peak (or trough) in m

Question 6

define time period

Answer 6

the time for one wave to pass a given point or the time for one complete oscillation in seconds (s)

Question 7

define frequency

Answer 7

the number of peaks passing a point per second (measured in Hz)

Question 8

What is a rarefaction?

Answer 8

A part of a longitudinal sound wave which has low pressure (wide bits - particles spread far apart)

Question 9

what is a compression?

Answer 9

a part of a longitudinal wave where the pressure is high

close together lines - because particles are squashed together

Question 10

state two examples of mechanical waves

Answer 10

sound waves, water waves

A mechanical wave is a wave that is an oscillation of matter, and therefore transfers energy through a medium.

Question 11

what is a mechanical wave?

Answer 11

a wave that needs medium or matter to travel through

Question 12

do electromagnetic waves require medium/matter to travel through?

Answer 12

no they do not, can travel through vacuum

Question 13

state an example of longitudinal waves

Answer 13

sound waves

Question 14

describe the way transverse waves trave;l

Answer 14

• direction of vibration is at right angles to the direction of travel of the wave

Question 15

how are transverse waves represented on a spring?

Answer 15

move up and down

Question 16

how are longitudinal waves represented on a spring?

Answer 16

pushed forward

• springs close together = compressions
• springs far apart = rarefactions

Question 17

describe one way to model waves

Answer 17

• ripples on water
  TRANSVERSE WAVE
  (surface of water moves up and down, waves travel, water does not) - showed by cork

Question 18

does air move when sound waves move?

Answer 18

no - sound is transferred through vibrating molecules, which stay where they are and vibrate about a fixed point

Question 19

what does a time trace diagram do?

Answer 19

• shows how displacement varies with time

- let us to measure the time period from any point on a wave to point in next

Question 20

what is the equation to find out the time period?

Answer 20

1
———
frequency

Question 21

what is the x-axis label on a snapshot diagram?

Answer 21

distance travelled

Question 22

what is the x-axis label on a time trace diagram?

Answer 22

time (in seconds)

Question 23

how are waves typically modelled?

Answer 23

using a ripple tank

Question 24

how do you measure the speed of both kinds of waves?

Answer 24

use a ripple tank

• know the frequency of ripples (by finding number of rotations of motor per second)
• know wavelength (by using a flashing light + ruler)

s = f x w

Question 25

explain why frequency is not ‘shown’ on diagrams

Answer 25

• Frequency is the number of waves per second

- you cannot show on a diagram.

Question 26

what is the equation to measure wave speed?

Answer 26

Wavelength (m) x Frequency (hz)

Question 27

difference between transverse and longitudinal waves (vibration of particles in terms of direction of travel)

Answer 27

o transverse = vibrations at right angles of direction of travel

o longitudinal = vibrations at same direction to direction of travel

Question 28

considering what kind of wave light travels as, is it a mechanical wave?

Answer 28

light travels as an electromagnetic wave

- so no, it is not a mechanical wave as it can travel without a medium (CAN TRAVEL IN A VACUUM)

Question 29

why can waves pass through faster in a solid compared to a gas?

Answer 29

as particles are very close together, so vibrations can be passed on very fast (faster wave speed)

Question 30

how is the amplitude related to the amount of energy a wave carries?

Answer 30

bigger amplitude = more energy the wave carries

Question 31

how are frequency and wavelength connected?

Answer 31

bigger wavelength = smaller frequency

Question 32

what is the equivilant to peaks and troughs in a longitudinal wave?

Answer 32

compressions (peaks)

rarefractions (troughs)

Question 33

what does the velocity of a wave depend on?

Answer 33

the medium that it is traveling through

Question 34

how are ripples on water surfaces used to model transverse waves

Answer 34

as if cork placed on the surface, it is not carried by the wave (only moves up and down)

Question 35

how can the speed of a transverse wave be measured using a ripple tank

Answer 35

1) light shone through tank
2) dark + light patches appear underneath it as light passes through crests + troughs
3) count number of times a dark patch passes through a point in a minute, divide by 60 = frequency
4) measure wavelength by the distance between each dark patch between waves
5) then use v = f x w to calculate speed