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Physics > Topic 6-Waves > Flashcards

Topic 6-Waves Flashcards

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1
Q

What do waves do?

A

Waves transfer energy

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2
Q

What is the wavelength?

A

Distance between the same points on two consecutive waves

Peak to peak/trough to trough

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3
Q

What is amplitude?

A

Distance from the equilibrium line to the maximum displacement (crest or trough)

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4
Q

What is frequency?

A

The number of waves that pass a single point per second

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5
Q

What is the wave period?

A

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

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6
Q

What is frequency measured in?

A

Hertz (Hz)

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7
Q

What are transverse waves?

A

Have peaks and troughs

Vibrations are at right angles to the direction of travel

Eg light, seismic s-waves, electromagnetic waves

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8
Q

What are longitudinal waves?

A

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

Has compressions and rarefactions

Eg sound waves, seismic p-waves

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9
Q

What are the two parts of a longitudinal wave called

A

Compressions and rarefactions

| | |||| | | |
^
compression

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10
Q

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

A

Reflection

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11
Q

How do sound waves travel through a solid?

A

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

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12
Q

What is the frequency range of human hearing?

A

20Hz-20,000Hz

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13
Q

What are ultrasound waves?

A

Waves that have a frequency higher than the upper limit of human hearing

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14
Q

Give an example use for ultrasound waves

A

Medical imaging

Industrial imaging

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15
Q

Describe how medical imaging uses ultrasound waves

A

Transducer is placed on the body and detects sets of ultrasound waves

Each ultrasound wave pulse is partially reflected from the different tissue boundaries in its path

It then returns to the transducer as a sequence of waves

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16
Q

What are some advantages of using ultrasound waves in medical imaging?

A

It can be used to scan organs and other soft tissues

Non ionising meaning it does not have enough energy to remove an electron to ionise and atom, meaning it is harmless

17
Q

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

A

Earth quakes

They produce both P-waves and S-waves

18
Q

Describe how industrial imaging uses ultrasound waves

A

Flaws in the metal castings can be detected using ultrasound waves

A flaw might be an internal crack, which creates a boundary inside the metal

Waves are partly reflected from this boundary

Waves are detected by transducer and displayed on an oscilloscope screen/computer monitor

19
Q

State a difference between the mediums that P-waves and S-waves can travel through

A

P-waves travel through both solids and liquids

S-waves only travel through solids (not liquids)

20
Q

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

A

Echo sounding

High frequency sound waves are emitted reflected and detected

Time difference between emission and detection alongside wave speed, are used to calculate distances

21
Q

There is no air in space

Astronauts in space cannot hear sounds from outside their spacesuits

Explain this

A

Sound cannot travel through free space because there are no particles to vibrate

22
Q

The frequency of an ultrasound wave used in a hospital is 2x10^6

It is not possible to produce ultrasound waves of this frequency using a tuning fork

Explain why

A

Frequency is very high so tuning fork would be very small

23
Q

What is an ultrasound?

A

It cannot be heard by humans

Above 20,000 hZ

24
Q

Ultrasound is used for pre-natal scanning. This is much safer that using X-rays. However, doctors were only sure ultrasound was safe after experiments of mice

Do you think the ultrasound experiments on mice were justified?

A

They were justified because ultrasound has been proved useful in medical and industrial processes

Unethical to experiment on humans so it is better to experiment of animals

25
Q

Explain what scientists should do if they find evidence that ultrasound may be harmful to human health?

A

Carry out more research to check reliability

26
Q

Describe the features of an x-ray is and what happens to this type of wave after it has entered the body

A

X-rays are electromagnetic waves that have a high frequency and high energy.

They have a short wavelength

When they enter the body they are absorbed by the bone

27
Q

Describe the features of ultrasounds and what happens to this type of wave after it has entered the body

A

Frequency above 20,000 Hz

Longitudinal

Beyond the human limit of hearing

Partially reflected at a boundary between two different medias

Travel at different speeds through different media

28
Q

Give uses of ultrasounds for medical treatments

A

Removing plaque from teeth

Removal of kidney stones

Repair of damaged tissue

29
Q

Describe the differences between longitudinal waves and transverse waves

A

The oscillation/vibration causing the wave for a transverse wave is perpendicular to the direction of travel

For a longitudinal wave, it is parallel to the direction of energy transfer

30
Q

Advantage of CT scanning

A

Easier to see a problem

Images have high resolution

31
Q

Disadvantage of CT scanning

A

X-ray scans are ionising

Mutates cells

32
Q

Explain how ultrasonic waves are used the image of an unborn baby

A

The waves are partially reflected when they hit a boundary between two medias

Time takes for reflected wave to return in used to produce image

33
Q

The diagram shows an ultrasound transmitter and detector fixed to the front of a metal block. The block has an internal crack

The diagram below shows the screen of the oscilloscope connected to the detector

Explain why pulse A and pulse B occur

A

Transmitted waves are partially reflected at boundary

Pulse A indicated the crack

Pulse B indicated the back of the crack

34
Q

What happens to the ultrasound which reaches the boundary between two different media and is not reflected?

A

It is absorbed and is transmitted/changes speed

Physics (10 decks)

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