Waves Flashcards

1
Q

What do waves transfer and not transfer?

A

Transfer: energy
Don’t transfer: matter

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2
Q

How are all waves produced?

A

Through vibrations.

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3
Q

What way do the vibrations move in a transverse wave?

A

Perpendicular to the direction in which the wave is travelling.

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4
Q

What way do the vibrations move in a longitudinal wave?

A

Parallel to the direction in which the wave is travelling.

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5
Q

What are the only two longitudinal waves?

A

Sound and ultrasound.

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6
Q

What is the wavelength of a wave? What is it usually measured in?

A

The distance between two consecutive crests or troughs. It is usually measured in metres, m.

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7
Q

What is the frequency of a wave? What is it usually measured in?

A

The numbers of waves that pass a point in one second. It is usually measured in Hertz, Hz.

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8
Q

What is the period of a wave? What is it usually measured in?

A

The time taken for one complete wave to pass a point. It is usually measured in seconds, s.

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9
Q

What is the amplitude of a wave? What is it usually measured in?

A

The MAXIMUM displacement of a wave from equilibrium position. It is usually measured in metres, m.

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10
Q

What is period related to? What is wavelength related to?

A

Period: time
Wavelength: distance

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11
Q

When the turns of a coil are close together what is it called?

A

A compression.

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12
Q

When the turns of a coil farthest apart what is the called?

A

Rarefaction

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13
Q

In terms of compressions and rarefactions, how do you find the wavelength of a longitudinal wave?

A

The distance between the centres of two consecutive compressions or rarefactions.

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14
Q

What is the wave equation?

A

Wave speed (v) = frequency (f) x wavelength (lambda)

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15
Q

What is the range of human hearing?

A

From 20 Hz to 20,000 Hz.

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16
Q

Sound at frequencies above 20 KHz cannot be heard and is called what?

A

Ultrasound.

17
Q

What is the name given to a reflected sound?

A

An echo.

18
Q

In terms of sound, what do hard surfaces do?

A

Reflect more sound and absorb less sound than softer surfaces.

19
Q

What animals can produce ultrasound?

A

Whales, bats and dolphins.

20
Q

Ultrasound has low wavelength, what does this mean?

A

They can be
-sent out in a very narrow beam
-focused on whatever is being investigated

21
Q

What is the best-known example of the use of ultra sound?

A

Medical imaging.

22
Q

Ultrasound is widely used in pre-natal scanning to check that the foetus is developing normally and to take measurements of its growth, but what measurements in particular?

A

The foetal head diameter.

23
Q

Ultrasound can be also be used on other organs or soft tissues such as the heart, kidneys, blood vessels and bladder, but why would this be?

A

To diagnose cancers.

24
Q

Aside from foetal head diameter checks and diagnosing cancers, what is another medical use of ultrasound?

A

The breaking down of kidney stones.

25
Q

What is the main industrial use for ultrasound?

A

To detect cracks or flaws in metals.

26
Q

Aside from detects defects in metals, what are some other industrial uses for ultrasound?

A

-Mapping the ocean floor in a field known as oceanography
-Cleaning sensitive electronic equipment
To detect layers of oil, coal, gas and other minerals deep underground.

27
Q

How can ultrasound be used in dentistry?

A

-Diagnostics: can be used to create images of the teeth and surrounding tissues, gum disease, cavities etc
-Cleaning: Ultrasonic scalets use high frequency sound waves to remove plaque from teeth.

28
Q

Why does a ship use ultrasound and not ordinary sound in this device?

A

-It is easier to concentrate ultrasound into a narrow beam
-Ultrasound can penetrate a greater depth of water
-Smaller objects can be located or scanned.

29
Q

Who uses microwaves as radar waves for navigation?

A

Air traffic controllers, pilots and masters of large ships.

30
Q

Why can only microwaves be used as radar waves for navigation, why can’t ultrasound waves?

A

As they do not travel fast enough. To track fast moving aircraft or more distant objects.