Waves

Question 1

What do waves transfer

Answer 1

Energy

Question 2

What don’t waves transfer

Answer 2

Matter

Question 3

How is it proven that waves only transfer energy

Answer 3

shown in the sea, where buoys stay still despite waves passing by them – the waves move, but not the particles

Question 4

What does wavelength mean

Answer 4

The distance between the same points on two consecutive waves

Question 5

What does frequency mean

Answer 5

The number of waves that pass a single point per second

Question 6

What does amplitude mean

Answer 6

Distance from equilibrium line to the trough

Question 7

What is a period

Answer 7

The time taken for a whole wave to completely pass a point

Question 8

What does a wavefront mean

Answer 8

The plane in which the wave travels (the direction of the wave

Question 9

How to do workout the velocity of a wave

Answer 9

wave speed (m/s) = frequency (Hz) ×
wavelength (m)
(v = f × λ)

Question 10

What is a transverse wave

Answer 10

the oscillations are perpendicular to the direction of energy transfer

Question 11

What is a longitudinal wave

Answer 11

the oscillations are parallel to the direction of energy transfer

Question 12

What is an example of a transverse wave

Answer 12

• any electromagnetic wave
• seismic S waves
• water waves

Question 13

What’s an example of a longitudinal wave

Answer 13

• Sound waves
• P waves

Question 14

How do you measure the velocity of soundwaves in the air

Answer 14

1. Make a noise at ~50m from a solid wall
2. Record how long it takes for the echo to be heard
3. Use speed = distance / time

Question 15

How do you measure the velocity of soundwaves in the air (using a microphone)

Answer 15

1. Have two microphones connected to a data logger at a large distance apart
2. Record the time difference between the sound passing from one to the other
3. Use speed = distance/time

Question 16

How do you measure the velocity of soundwaves on water surface (using a stroboscope)

Answer 16

1. Use a stroboscope which has the same frequency as water waves
2. Measure the distance between the ‘fixed’ ripples
3. Use 𝑣 = 𝑓𝜆

Question 17

How do you measure the velocity of soundwaves on water surface

Answer 17

1. Move a pencil along the paper at the same speed as a wavefront
2. Measure time taken to draw the line / measure the length of the line
3. Use speed = distance/time

Question 18

Describe refraction

Answer 18

• waves pass from one medium to another
• If passing into a denser medium (i.e air to glass) wave will refract TOWARDS the normal

Question 19

Describe what happens when a wave is refracted into a denser medium

Answer 19

• Speed of wave decreases
• Wavelength decreases
• Energy is constant

Question 20

Describe reflection

Answer 20

Waves reflect off a flat surface

Question 21

How do different surfaces affect reflection

Answer 21

The surface: * smoother the surface the stronger the reflected wave is
* Rougher the surface the more the light will scatter

Question 22

What is transmission

Answer 22

When waves pass through a transparent material

Question 23

What is absorption

Answer 23

Energy taken in by a material

Question 24

Why may certain substances absorb, transmit, refract or reflect waves differently

Answer 24

Due to different wavelengths

Question 25

How does the ear work

Answer 25

1. Sound causes air particles in our ear canal to vibrate and hit the eardrum. 2. The eardrum vibrates, passing these vibrations to three small ear bones: hammer, anvil, and stirrup. 3. The stirrup hits the cochlea, converting vibrations into an electrical signal sent to the brain via the auditory nerve. Our brain then translates this signal into sound.

Question 26

What are compressions

Answer 26

regions of higher density

Question 27

What are rarefactions

Answer 27

Regions of lower density

Question 28

What is the range of frequency a human can hear

Answer 28

20Hz to 20000Hz

Question 29

What is the process of sound going through different states of matter

Answer 29

Wavelengths get longer as speed increases in higher density mediums (solids) Wavelengths get shorter as speed decreases in lower density mediums (air)

Question 30

What are frequencies under 30 called

Answer 30

infrasounds

Question 31

How is ultrasound used for foetal scanning

Answer 31

ultrasound waves partially reflect at each surface boundary, this can be used to work out the distances and therefore an image of the foetus

Question 32

How is ultrasound used for sonar

Answer 32

Pulse of ultrasound is sent below a ship, and the time taken for it to reflect and reach the ship can be used to calculate the depth

Question 33

Explain how hearing processes only work over a limited frequency range

Answer 33

Higher the frequency = more energy transferred Damages cells in the ear

Question 34

What has a frequency below 20Hz

Answer 34

Infrasound

Question 35

What are P waves and what can it pass through

Answer 35

Longitudinal Can pass through solids and liquids

Question 36

What are S waves and what can they pass through

Answer 36

Transverse Solids

Question 37

How can S and P waves be used to explore the earths core

Answer 37

On the opposite side of the Earth when an earthquake occurs only P waves are detected, suggesting the core of the Earth is liquid – hence no S waves can penetrate it