SP4 Waves

Question 1

What do waves transfer

Answer 1

Energy and information but not matter

Question 2

Two types of waves are

Answer 2

Transverse and longitudinal

Question 3

Examples of transverse waves

Answer 3

Water surface waves
Seismic S waves
All electromagnetic waves (light, heat, radio, micro, x rays, UV, gamma)

Question 4

Examples of longitudinal waves

Answer 4

Sound waves

Seismic P waves

Question 5

What are transverse waves

Answer 5

Waves where the vibrations are at right angles to which the direction the waves is travelling. The particles move up and down

Question 6

What are longitudinal waves

Answer 6

Waves where the vibrations are parallel to the direction which the wave is travelling e.g in a sound wave. Particles move backwards sand forwards in the direction of travel.

Question 7

What is the equation relating wave speed, frequency and wavelength

Answer 7

Wave speed = frequency x wavelength

Question 8

What is the wave speed when the frequency=100 and the wavelength=8

Answer 8

800 (m/s)

Question 9

What is the equation relating wave speed, distance and time.

Answer 9

Wave speed = Distance / time

Question 10

What is the wave speed of a wave with a distance=300 m and a time of 3 s

Answer 10

100 (m/s)

Question 11

Describe how to measure the velocity of sound in air.

170m =

Answer 11

Divide the distance in metres by the average time in seconds.
For example 170 metres divided by 0.50 seconds = 340 m/s

Question 12

What is refraction.

Answer 12

Refraction is the change in direction of a wave passing from one medium to another caused by its change in speed.

Question 13

Describe how the direction of a wave changes when it goes from one material to another.

Answer 13

Waves change speed when they pass across the boundary between two different substances, such as light waves refracting when they pass from air to glass. This causes them to change direction and this effect is called refractio

Question 14

Explain some effects of the refraction of light

Answer 14

Light waves change speed when they pass across the boundary between two substances with a different density , such as air and glass.

Question 15

Explain how a change in wave speed can cause a change in direction.

Answer 15

Waves change speed when they pass across the boundary between two different substances, such as light waves refracting when they pass from air to glass.

Question 16

Describe some effects of waves being reflected.

Answer 16

The reflection of sound causes echoes.

The law of reflection states that:

angle of incidence = angle of reflection

For example, if a light ray hits a surface at 32°, it will be reflected at 32°.

Question 17

Describe some effects of waves being absorbed or transmitted.

Answer 17

When waves are absorbed by a surface, the energy of the wave is transferred to the particles in the surface. This will usually increase the internal energy of the particles. When white light shines on an opaque object, some wavelengths or colours of light are absorbed.

Question 18

Describe how changes in velocity, frequency and wavelength are related when sound waves go from one medium to another.

Answer 18

When sound waves move from one medium to another, there will be changes to the velocity (or speed), frequency and wavelength of the sound wave. … the wavelength of the sound wave decreases. the frequency of the sound wave stays the same. the velocity of the sound wave decreases (since wave speed = frequency × wavelength)

Question 19

List the parts of the human ear, in the order in which they transmit vibrations.

Answer 19

Ear canal, Eardrum, Hammer, Anvil, Stirrup (Ossiciles), Cochlea, Auditory nerve

Question 20

Function of the Eardrum

Answer 20

Transfers vibrations from air to bones

Question 21

Function of the Cochlea

Answer 21

Convert vibrations into nerve impulses

Question 22

Function of the Ear canal

Answer 22

Channels sound waves into the head

Question 23

Function of the Ossicles

Answer 23

Transfers vibrations from the eardrum to the cochlea

Question 24

Function of the Auditory nerve

Answer 24

Transmits nerve impulses to the brain

Question 25

Function of the Tiny bones (Hammar)

Answer 25

Amplifies vibratins

Question 26

Describe how sound waves in air are converted to vibrations in solids.

Answer 26

Sound waves can travel through solids causing vibrations in the solid. Within the ear, sound waves cause the ear drum and other parts to vibrate which causes the sensation of sound. The conversion of sound waves to vibrations of solids works over a limited frequency range. This restricts the limits of human hearing.

Question 27

Describe some factors that affect how well sound waves transfer energy to solids.

Answer 27

The stronger the particle interactions are, the more quickly the wave is transferred. So in general, sound travels faster in solids than in liquids, and faster in liquids than in gas. Temperature actually increases the speed of sound, because warmer particles generally move at a faster rate.

Question 28

Explain why the human ear can only detect a certain range of frequencies.

Answer 28

The range of frequencies that a person can hear depends on the range of lengths of hairs in the cochlea. As a person ages, the shorter hairs that respond to higher frequencies stop working - this means that people tend to lose the ability to hear higher frequencies of sound as they grow older.

Question 29

What is the depth of water equation

Answer 29

Distance = Speed x time

Question 30

What frequency is classed as ultrasound

Answer 30

20,000 Hz

Question 31

Explain how ultrasound is used in sonar.

Answer 31

Sonar equipment carried on ships or submarines which uses a pulse of ultrasound. This used to detect fish or depth of the sea.

Question 32

Describe uses of ultrasound in body scanning.

Answer 32

Ultrasound can be used for imaging inside the body. This is used for pregnant women's to track how the fetus is developing. A gel is used to stop the ultrasound reflecting from the skin. The probe emits and receives ultrasound waves. Some sound is reflected when the ultrasound waves pass into a different medium, such as fat or bone.

Question 33

What frequency is classed as infrasound

Answer 33

Below 20 Hz

Question 34

Describe some uses of infrasound.

Answer 34

Infrasound can be used to investigate the internal structure of our planet. Earthquakes produce very powerful seismic waves that can be classed as infrasound waves. Seismic waves from large earthquakes are detected around the world.

Question 35

What are seismic waves

Answer 35

Vibrations caused by the earthquakes energy that is released

Question 36

What is a P wave and what can it travel through

Answer 36

A P wave is a sound wave traveling through rock. In a P wave, the rock particles are alternately squished together and pulled apart (called compressions and dilatations), so P waves are also called compressional waves. These waves can travel through solids, liquids, and gases as shown by their shadow zone on the earth.

Question 37

What is a S wave and what can it travel through

Answer 37

An S wave, or shear wave, is a seismic body wave that shakes the ground back and forth perpendicular to the direction the wave is moving. . They can propagate through solid rocks because these rocks have enough shear strength. The shear strength is one of the forces that hold the rock together, preventing it from falling into pieces. Liquids lack shear strength.

Question 38

Explain how seismic waves can help us to investigate the Earth’s core.

Answer 38

Refractions between layers cause two shadow zones, where no P waves are detected – the size and positions of these shadow zones indicate there is a solid inner core.