Topic 4 - waves

Question 1

What do waves transfer?

Answer 1

Energy and information

Question 2

What are the two types of waves?

Answer 2

Transverse

Longitudinal

Question 3

What is a transverse wave?

Answer 3

A wave for which the oscillations are perpendicular to the direction of energy transfer

Question 4

What is a longitudinal wave?

Answer 4

A wave for which the oscillations are parallel to the direction of energy transfer

Question 5

Give two examples of transverse waves

Answer 5

Seismic S-waves

Electromagnetic

Question 6

Give two examples of longitudinal waves

Answer 6

Sound waves

Seismic P-waves

Question 7

What are the two parts of a longitudinal wave called?

Answer 7

Compressions and rarefactions

Question 8

What are the two parts of a transverse wave called?

Answer 8

Peaked and troughs

Question 9

What is a wave’s amplitude?

Answer 9

The maximum displacement of a point on a wave from its undisturbed position

Question 10

What is wavelength?

Answer 10

The distance from a pint on.a wave to the same position of the adjacent wave
Most commonly peak to peak or trough to trough

Question 11

What is the frequency of a wave?

Answer 11

The number of waves that pass a given point each second

Question 12

What is the unit used for frequency?

Answer 12

Hertz

Question 13

What is meant by a frequency of 200Hz?

Answer 13

200 waves pass a given point each second

Question 14

What is wave speed?

Answer 14

The speed at which energy is transferred through a medium

Question 15

What is wave velocity?

Answer 15

The product of the wavelength and frequency of the wave

Question 16

What is the equation to calculate wave speed?

Answer 16

Frequency x wavelength

Question 17

What is meant by the period of the wave?

Answer 17

The length of time it takes for one full wave to pass through a point

Question 18

What word is used to describe when a wave bounces off a surface?

Answer 18

Reflection

Question 19

What is the normal (in terms of reflection and refraction)?

Answer 19

A vertical imaginary line which is perpendicular to the boundary

Question 20

What occurs when light is reflected off a boundary?

Answer 20

It bounces off a smooth flat surface so that the angle of incidence is the same as the angle of reflection

Question 21

What is refraction?

Answer 21

The change in speed of a wave as it reaches a boundary between two media, usually resulting in a change in direction

Question 22

What occurs when a light is refracted at a boundary?

Answer 22

The light changes speed and direction in the new medium

Question 23

When entering a denser medium, light waves…

Answer 23

Slow down and bend towards the normal

Question 24

When entering a less dense medium, light waves…

Answer 24

Speed up and bend away from the normal

Question 25

How can refraction be measured?

Answer 25

The angle of incidence and the angle of refraction can be measured and compared

Question 26

What are the effects of absorption of different wavelengths of waves in different mediums?

Answer 26

Some materials behave differently depending on the wavelength

Question 27

How do sound waves travel through a solid?

Answer 27

The particles in the solid vibrate and transfer kinetic energy through the material

Question 28

How does the human ear work?

Answer 28

The outer ear collects the sound which travels into the ear The sound waves cause the eardrum to vibrate at the same frequency This is amplified by three ossicles This causes the hair in the cochlea to vibrate The cochlea converts the vibrations into electrical signals The signals are passed to brain through auditory nerve The brain converts the electrical signals into sound

Question 29

What is the frequency range of human hearing?

Answer 29

20Hz - 20kHz

Question 30

What is an ultrasound wave?

Answer 30

A sound wave with a frequency greater than 20,000 Hz

Question 31

What is sound of frequencies less than 20Hzcalled?

Answer 31

Infrasound

Question 32

What natural event causes deistic waves to be produced? What types are produced?

Answer 32

Earthquakes | They produce both P-waves and S-waves

Question 33

Are P waves transverse of longitudinal?

Answer 33

Longitudinal

Question 34

Are S waves transverse of longitudinal?

Answer 34

Transverse

Question 35

What mediums can P waves travel through?

Answer 35

Both solids and liquids

Question 36

What medium canS waves travel through?

Answer 36

Only solids

Question 37

What is the significance of P and S waves?

Answer 37

They provide evidence that the Earth has a liquid core; only P waves produced by an earthquake can be detected in the other side of the globe

Question 38

What technique is used to detect objects in deep water and measure water depth?

Answer 38

Echo sounding

Question 39

How does sonar work?

Answer 39

When ultrasound d waves are emitted they reflect off boundaries and their echos are detected The speed of the ultrasound is known and also the time it takes to detect the echos The equation: distance = speed x time is used to find the distance travelled The distance travelled is halved to give the distance between emitted and boundary

Question 40

How does foetal scanning work?

Answer 40

An untranslated d wave is sent into the patient’s body It passes through body and reflects off the organs and tissue The device then uses the reflected ultrasound d waves to produce and image of the foetus Ultrasound is safe and therefore does not damage cells