P12 - Sound Flashcards

1
Q

speed of sound and temp

A

varies with temp

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2
Q

speed of sound

A

340 m/s @ 15.c

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3
Q

sound and a vacuum

A

cannot travel through a vacuum

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4
Q

compressions and rarefactions

A

as the object vibrates
-pulls/pushes repeatedly on air

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5
Q

sound and ear

A

as the object vibrates
-pulls/pushes repeatedly on air
-wave reaches ear
-makes eardrums vibrate
-send signals to brain

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6
Q

why is sound longitudinal

A

-air vibrates along direction of energy transfer

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7
Q

how to investigate waves methods

A

-ripple tank for water waves
-stretched string for waves in a solid
-signal generator/loudspeaker for sound waves

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8
Q

echo

A

reflection of sound that can be heard
-smooth hard surfaces (bare walls)

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9
Q

time delay

A

time taken for sound to travel to wall + back

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10
Q

speed of echo

A

-distance to wall and back/time delay

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11
Q

why can sound not travel through a vacuum

A

no matter for vibrations to work on

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12
Q

increasing loudness =

A

increasing amplitude (taller wave)

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13
Q

pitch increases =

A

frequency increases

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14
Q

hearing range for humans

A

20 Hz to 20KHz

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15
Q

why do humans have a limited hearing range

A

-conversion of sound waves to vibrations only happens over a limited frequency range

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16
Q

how do vibrations travel through a solid

A

-sound entering a solid is converted into vibration
-able to travel through

17
Q

speed of sound changes as

A

-mediums vary

18
Q

changes when sound moves from 1 medium to another

A

no change in frequency
-change in speed/wavelength

19
Q

echo sounding purposes

A

-pulses of high frequency sound waves are sent to detect object in deep water
-measures water depth below ship

20
Q

echo sounding works by

A

-pulses are reflected by object
- detected by receiver at same height as transmitter
-time is measured

21
Q

formula for depth of water by echo sounding

A

0.5 x speed x time

22
Q

ultrasound waves

A

above frequency humans can detect
-above 20kHz

23
Q

uses for ultrasound waves

A

-prenatal scans
-images of organs
-

24
Q

scanning with ultrasound method

A

-transducer placed on body surface and displays on screen

25
transducer
produces and detects pulses /ultrasound waves
26
how do ultrasounds work
-waves are partially reflected from diff tissue boundaries in its path -waves are returned to transducer as a sequence of reflected waves arriving at diff times -forms image on a screen
27
pros of ultrasound use
used to scan organs/ soft tissues (unlike x rays) -non ionising = harmless
28
non ionising
not enough energy to remove an electron to ionise an atom
29
Industrial imaging and ultrasounds purpose
-flaws in metal castings can be detected
30
Industrial imaging and ultrasounds method
-transducer sends waves into block -ultrasound waves are partly reflected + detected -displayed on screen
31
ultrasound formula for distance travelled by wave
speed of ultrasound waves x time taken