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Physics > Sound and electromagnetic waves > Flashcards

Sound and electromagnetic waves Flashcards

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1
Q

Def a longitudinal wave

A

Is a disturbance - the displacement of which is in the direction of propagation

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2
Q

Define a wavelength

A

Is the distance between 2 corresponding points on two successive waves

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3
Q

Define frequency

A

It is the number of waves passing a given point in one second

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4
Q

Define Amplitude

A

It is the maximum displacement attained from the undisturbed position

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5
Q

What is the formula for the speed of sound

A

V=d/t

v = velocity in m/s
d = distance travelled in m
t = time in s

Also v = lambda x f

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6
Q

Describe an experiment to determinethe speed of sound

A

Tapemeasure
Stopwatch
Starters pistol

500m open field
3 pupils with stopwatches on one side
Another pupil 500m away firing the pistol
Stopwatches started when smokeis seen and stopped when sound is heard
Average of 3 times calculated
Use formula to calculate v=d/t

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7
Q

Name 4 facts about sound

A

Travels faster at higher temperatures

Travels faster and better in liquids than air

Solids transmit sound best, fastet, and furthest

Greter speed in liquid and solids due to greater elasticity

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8
Q

Define an echo

A

It is a repetition/s of sound caused by the reflection of soundwaves from a hard surface such as a wall or cliff

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9
Q

Name 3 conditions necessary to form an echo

A

Loud enough sound

Large enough reflective surface (rock / wall)

Far enough from reflective surface (17m)

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10
Q

Name 3 characteristics of sound

A

Pitch

Loudness

Quality

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11
Q

What attribute of a wave cause the pitch of sound

A

Frequency

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12
Q

Name 3 factors that determine the pitch of a piano string

A

Length

Thickness

Tension

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13
Q

What attribute of a wave cause loudness

A

Amplitude

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14
Q

What cause the quality of a note

A

Faint overtones formed along with the fundamental note

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15
Q

What is meant by the quality of a note

A

It determines the difference in sound between a note played on a piano and the same note played on a violin

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16
Q

What are the limits that the human ear is capable of hearing

A

20Hz - 20000Hz

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17
Q

At what frequency do we describe ultrasound

A

20 000Hz and higher

18
Q

Give 4 uses of ultrasound

A

Image the human body -diagnostic tool

Industrially to find flaws in material and measure thickness of objects

As a non invasive sensor to detect the content of containers

To break up kidney stones without surgery

19
Q

Difference between a misical note and noise

A

Noise is caused by irregular vibration while a musical note is caused by a regular vibration

20
Q

Def electromagnetic waves

A

Are progressive transverse waves that are made up of alternating electric and magnetic fields that are at right angles to each other

21
Q

In what respect are all electromagnetic waves the same

A

They all travel at the same speed. 3 x 10 ^8m/s

22
Q

Electromagnetic waves differ from each other in respect to ……… And …….

A

Frequency

Wavelength

23
Q

Give 6 properties of EM waves

A

Can travel through a vacuum

Are transverse waves

Travel at a speed of 3 x 10^8 m/s in a vacuum

Exhibit reflection, refraction, diffeaction, interference and polarization

Transmit energy from one place to another

Can be absorbed by matter to cause heating and other effects

24
Q

How are radio waves produced?

A

By oscillating currents in an aerial

25
Q

A radio receiver does not need to be in line of sight from the transmitter to receive the signal - explain

A

Radiowaves can be diffracted or reflected around obstacles

Long wave transmission is ised in mountainous areas because long waves are diffracted better over the mountain tops - so that transmissions can be received in the valleys.

They are also reflected by charged particles in the ionosphere which makes long distance world service radio reception possible aroun the curvature of the earth

26
Q

Microwaves are at the Short /Long wavelength end of the radio band

A

Short

27
Q

Microwaves are used for

A

Cooking in microwave ovens

For communication by cell phone and with satellites

28
Q

Infrared radiation is characterized by

A

Heat

29
Q

Infrared can be detected by

A

Skin

Thermometer

Temperature sensitive photographic film

30
Q

What is infrared radiation used for

A

Trigger burglar alarms

In remote controlls for TVs

In heaters toastera and grills

To transmit communication signals in optical fibre cables

31
Q

White light can be split in all the component colours / spectrum of light

Name the colours in decending wavelength

A 
Red
Orange
Yellow
Green
Blue
Indigo
Violet
32
Q

Def monochromatic light

A

Light of one colour and therefore of one frequency

33
Q

Ultraviolet rays causes

A

Sunburn

34
Q

Name uses for ultraviolet radiation

A

Sunbed
Security pens
Fluorescent lights
Killing virusses and bacteria

35
Q

How are x rays produced

A

In an x ray tube when high velocity electrons strike a metal target

36
Q

How are gamma rays produced

A

Radioactive decay of unstable atoms

37
Q

How can we detect gamma rays

A

Geiger counter

38
Q

What is gamma radiation used for

A

Sterilize surgical instruments

To kill harmful bacteria in food

To kill cancer cells

39
Q

List electromagnetic waves from longest to shortest wavelength

A

Radio waves

Micro waves

Infra red waves

Visible waves

Ultraviolet

X rays

Gamma rays

40
Q

Def sound waves

A

Are longitudinal waves that are Made up of a series of compressions and rarefactions caused by vibrations

41
Q

Define the electro magnetic spectrum

A

It is a full and continous range of wavelengths of electromagnetic waves

Physics (17 decks)

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