Topic 4- Waves

Question 1

What do waves transfer?

Answer 1

• Energy
• Not matter

Question 2

How do we know matter doesn’t move in sound and light waves?

Answer 2

Light- particles oscillate up and down
Sound- particles vibrate back and forth

• Ducks (toy) don’t move in water

Question 3

What is frequency?

Answer 3

How many waves per second

Question 4

What is wavelength?

Answer 4

Length of a full wave, from peak to peak

Question 5

What is amplitude?

Answer 5

• The height, equilibrium to the peak/trough
• Loudness of a sound wave/ brightness

Question 6

What is the period?

Answer 6

How many seconds it takes one complete wave to pass a point.

Question 7

What is the wave velocity?

Answer 7

• Speed of the wave in a given
  direction
• changes in different mediums

Question 8

What is a wavefront?

Answer 8

• Lines that show the peak of a wave that vibrate in unison.
• Equal distance from eachother

Question 9

What is a longitude wave?

Answer 9

• A wave with areas of compression and rarefaction
• Oscillations occur parallel to the energy movement
• sound waves

Question 10

What is a transverse wave?

Answer 10

• Wave with a peak and trough
• Oscillations occur perpendicular to the energy movement
• Light/electromagnetic waves

Question 11

What are two examples of longitudinal waves?

Answer 11

• Sound
• P seismic

Question 12

What are three examples of transverse waves?

Answer 12

• Electromagnetic (light)
• S seismic
• Water

Question 13

What are properties of P seismic waves ?

Answer 13

• Can travel through solids and liquid
• Produced by earthquakes
• Faster than S seismic

Question 14

What are properties of S seismic waves ?

Answer 14

• Slower than P seismic
• Only travel through solids
• More destructive

Question 15

How do we calculate wave speed?

Answer 15

Wave speed= frequency x wavelength
v=fxλ

Question 16

Describe how to measure the velocity of sound in air with humans + what are the issues?

Answer 16

1) Place two people across a measured distance (e.g 100m)
2) Person A makes a visual and noise making gesture (e.g loud clap)
3) Person B beings top watch when sees and ends when hears
4) Repeat
5) Human reaction times differ for sound + light

Question 17

Describe how to measure the velocity of sound in air in microphones?

Answer 17

1)Place 2 microphones 1 metre apart
2)attach to a computerised ossciloscope
3)Make a loud bang at microphone 1
4)M-1 and M-2 will pick up sounds at different times

Question 18

Describe how to measure the velocity of sound in ripples?

Answer 18

1) Ripple tank
2) Record waves movement
3) Find frequency by calculating how many waves pass a point per second
4) Find wave fronts (shadow) and measure the distance
5) Use wavespeed= wavelength x frequency

Question 19

Core Practical: Investigate suitibility of equipmenent to find the frequency, speed and wavelength of a wave in a fluid

Answer 19

1) Record a ripple tank (frequency =no. of waves per second)
2) Place ruler udner ripple tank + use shadows to find wavelength
3) Wave speed = wavelength x frequency

Question 20

Core Practical: Investigate suitibility of equipmenent to find the frequency, speed and wavelength of a wave in a solid

Answer 20

1) Suspend metal rod with a clamp stand and a rubber band
2) Attach data logger and 2 microphones to each end
3) Start data logger (short time so more precise)
4) Hit one end with hammer
5) Micropohones pick up sound and when it eaches the other end (in data logger) -the time
6) Use distance/time= speed

Question 21

How to calculate depth from time and speed of a wave?

Answer 21

(time/2)x speed

Question 22

What is transmission

Answer 22

-Wave passes through an object without being absorbed

Question 23

What is reflection?

Answer 23

-Wave bounces off the boundry between 2 different mediums
-Angle of incidence= Angle of reflection

Question 24

What is refraction?

Answer 24

1) An wave speeds up/ slows down when entering a materil with a different density
2) To keep the same frequency, its wavelength shorterns (all inter-related)

incidence ray, refracted ray and emergant ray

Question 25

Do sound waves speed up or slow down in denser mediums?

Answer 25

-speed up -Longitudinal, closer particles | opposite for light

Question 26

If a wave slows down it bends which way when refracted?

Answer 26

Towards the normal line (90 degrees to object) | e.g light in denser, sound in less dense

Question 27

How do objects interact with different wavelengths?

Answer 27

-differently -some absob/ transmit/ reflect -e.g why we see colour

Question 28

Parts of the human ear?

Answer 28

1) Ear canal 2) Ear drum 3) Ossicles (3 small bones) 4) semicircular canals 5) Cochlea 6) Auditory nerve

Question 29

How do humans hear?

Answer 29

-Sound is filtered into + travels along ear canal -Cuases ear drum to vibrate -Osiccles and semicircular canals transmit to cochlea -Cochlea converts into electrical signal -Across auditory nerve to brain to be interprited | e.g higher frequency = higher pitch

Question 30

Avg hearing range of humans?

Answer 30

20 Hz--->20,000 Hz | decreases when older due to wear + tear

Question 31

What is ultrasound?

Answer 31

sound with greater frequency than **20,000 Hz**

Question 32

What is Infrasound?

Answer 32

sound with lower frequency than **20 Hz**

Question 33

What can we use ultrasound for?

Answer 33

-Foetal scanning -Sonar -Industry poroducts -Medical e.g kindey stone breaking

Question 34

How does feotal scanny work?

Answer 34

-Use an emitter + reciever on stomach -Reflected when reach boundry -processed into 3D image | safer than x-ray as less energetic (lower frequency), non ionising

Question 35

How does ultrasound work for industry work?

Answer 35

-Air in any cracks -Ulttrasound is reflected too ealy -reflected from boundry of product to air

Question 36

How does ultrasound work for sonar work?

Answer 36

- Ultrasound emitted then reflected back t boundry to other density objects

Question 37

How does ultrasound work for kidney stones work?

Answer 37

-vibrates into smaller peices | non ionising

Question 38

How is infrasound used for discorvering earth's core?

Answer 38

-**P seismic** waves travel through **liquid + solid** -**S seimsic** only though **solid** -S seismic found on same half of Earth as earthquake, wherease P everywhere + increased refraction -Suggests their is liquid outer core -Region where no waves are detected due to gradual refractions through mantle + liquid outer core

Question 39

What measures seismic waves?

Answer 39

seismometer