Ch - 12 (Sound)

Question 1

How are sound waves produced?

Answer 1

vibrating sources

Question 2

What type of wave do sound waves travel in?

Answer 2

Longitudinal ( back and forth )

Question 3

Can sound travel in vacuum?

Answer 3

No, it needs a medium and particles to pass through.

Question 4

What are 2 things a longitudinal wave consists of?

Answer 4

Compression
Rarefaction

Question 5

What is a compression?

Answer 5

A region of higher density (ex - molecules are bunched together)

Question 6

What is a rarefaction?

Answer 6

A region of lower density (ex - molecules are spread further apart)

Question 7

What other type of wave is sound considered due to the changes in pressure?

Answer 7

Pressure wave

Question 8

How is sound transferred?

Answer 8

Sound particles are produced, energy is passes on through vibrations, and sound reaches our ears.

Question 9

How is the pressure in compression and rarefaction?

Answer 9

• Compression (High pressure)
• Rarefaction (Low pressure)

Question 10

What is the speed of sound in air?

Answer 10

330 - 350 m/s

Question 11

What is the speed of sound in liquid?

Answer 11

1500 m/s

Question 12

What is the speed of sound in solid?

Answer 12

5000 m/s

Question 13

What are the different methods to measure speed of sound?

Answer 13

Method 1: Measuring sounds between 2 points

Method 2: Using echoes

Method 3: Using an oscilloscope

Question 14

What is the apparatus required for (Method 1: Measuring sounds between 2 points)?

Answer 14

• Trundle wheel
• two wooden blocks
• stopwatch

Speed = d/t

Question 15

What is the apparatus required for (Method 2: Using echoes)?

Answer 15

• Trundle wheel
• 2 wooden blocks
• stopwatch

Speed = 2 x d / t

Question 16

What is the apparatus required for (Method 3: Using an oscilloscope)?

Answer 16

• Microphone
• oscilloscope
• tape measure

Speed = d between microphones / time between peaks

Question 17

Which of the three methods are most accurate?

Method 1: Measuring sounds between 2 points

Method 2: Using echoes

Method 3: Using an oscilloscope

Answer 17

Method 3 because timing is done automatically.

Question 18

which of the three methods is the least accurate?

Method 1: Measuring sounds between 2 points

Method 2: Using echoes

Method 3: Using an oscilloscope

Answer 18

Method 1 because the time intervals are very short

Question 19

What is the method to measure wave speed in water?

Answer 19

By creating ripples in water

Apparatus:
- Tape measure
- stopwatch

Procedure:
- disturb the water

• time how long it takes for the First ripple to reach the other person

Speed = distance travelled / time taken

Question 20

What part of the wave determines the pitch?

Answer 20

Frequency

Question 21

What part of the wave determines loudness?

Answer 21

Amplitude

Question 22

What happens in High pitch and low pitch?

Answer 22

High pitch : High frequency

Low pitch : Low frequency

Question 23

What happens in a loud and soft sound?

Answer 23

Loud : High amplitude

Soft : Low amplitude

Question 24

What is an echo?

Answer 24

The reflection of a sound wave off a surface is called an echo

Question 25

what can echoes be used to measure?

Answer 25

• Depth
• To detect objects underwater

Question 26

What can echoes do to measure the depth?

Answer 26

• A sound wave can be transmitted from the surface of the water
• sound wave is reflected from the bottom

Question 27

What measurements are used to measure the depth of the water?

Answer 27

the time it takes for sound waves to return

Question 28

What measurement is used to measure the depth of the ocean?

Answer 28

The distance the wave travels is twice the depth of the ocean

Question 29

What is the range that humans can hear up to?

Answer 29

20 - 20,000 Hz

Question 30

Define ultrasound.

Answer 30

it is the name given to the sound wave with a frequency greater than 20,000 Hz

Question 31

What happens when ultrasound reaches a boundary between 2 media?

Answer 31

Some of the waves are partially reflected.

The remainder of the wave is transmitted.

Question 32

What are ultrasound transducers able to do?

Answer 32

• Emit ultrasound
• Recieve ultrasound

Question 33

How can ultrasound be used to determine how far a boundary is?

Answer 33

because ultrasound travels at different speeds through different media.

Question 34

What is the equation to use?

Answer 34

v = s / t

v = speed in metres per sec

s = distance in metres (m)

t = time taken in sec (s)

Question 35

How is ultrasound used in medicine?

Answer 35

• construct images of the foetus
• to generate 2D images of organs and internal structures (that are not surrounded by a bone)
• medical treatment to remove kidney stones

Question 36

What is an ultrasound detector made out of?

Answer 36

Transducer that produces a beam of ultrasound waves into the body.

Question 37

What does the ultrasound detector do?

Answer 37

• Ultrasound waves are reflected back to the transducer by boundaries between tissues in the path of beam
• The echoes hit the transducer, they generate electrical signals, are sent to ultrasound scanners.
• the speed of sound and eco od each is measured and shown

Question 38

What happens when you take a series of ultrasound?

Answer 38

The time measurements are used to build up an image.

Question 39

What is different about ultrasound scanners?

Answer 39

It is non - invasive and harmless

Question 40

How is ultrasoud used in the industry?

Answer 40

• Check for cracks inside metal objects
• generate images beneath the surface

Question 41

How can the ultrasound be sued for a crack inside a metal ibject?,

Answer 41

• cause some waves to reflect earlier than rest, it will show up as pulses, on oscilloscope
• each pulse represents the time the wave crosses the boundary.